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MichaelDT

macrumors regular
Original poster
Aug 18, 2012
204
235
iMac 2009 to 2011 MXM3 graphics card upgrade
(Lastest update 05/24/2024 - this is the official documentation page - you found it finally!)

This is the single and only documentation post
. During the last years we constantly updated this post to reflect the lastet development of vBIOS and OCLP. There is no other documentation and you can ignore most of the more than 800 pages of posts!

Goal of this thread and this particular post is to provide tools, information, software and some assistance to upgrade your iMac using a working metal MXM3 slot GPU opening the gates to most recent macOS versions including Mojave, Catalina, Big Sur, Monterey, Ventura, and possibly Sonoma. We do not provide help to repair or revive broken graphics cards, this is out of scope.

This is not really a plug and play solution! You need some macOS / Unix system administration knowledge, the ability to run programs from the Terminal app and some manual skills to assemble your iMac again. If you have not done this before, get some local help in advance and make a complete plan, get the tools, make notes while reading through this page several times and check the thread! Get a card, wait for another rainy Sunday and start your project and have fun!

It is HIGHLY recommended that you read through this post, open all known issues sections in all spoiler sections below, check the FAQ section before asking questions. Then, reread the information. This forum does not provide internal page links, therefore we have to use the SPOILER tags to force some structure into this long and complex post. Just open the SPOILER sections to discover more information.

Before you post a question please add a signature to your account settings reflecting your machine type, graphics card, and possible even the problem you have. This signature sticks with every post you make and helps other to keep track and understand what is going on. If you do not get an answer you likely ignored to read this docs.

Q: Which graphics card will work at all?

Only cards fitting into the MXM3 slot can be installed in the iMacs models listed below. Older iMacs have an MXM2 type slot which is incompatible with newer MXMX3 cards.

Q: Which MXM3 card will physically fit into my iMac?

There are smaller MXM-A cards which can be physically installed in all systems listed below. No heat sink mod needed! (see picture attached to post).

There are bigger MXM-B cards running stablely only in the 27" models. These cards can be installed into a 21.5" or 24" model MXM3 slot, but will be unstable due to their high power draw, will not fit onto the smaller heat sink, will over heat the iMac after a short while or simply not boot. Do not try it and do not ask for support!

Nearly all those MXM-B cards need the big three copper pipe MXM-B heat sink from the 27" mid 2011 model with the 6970M card to get the generated heat out of the system under load - and all NVIDIA need a heat sink mod with a Dremel (see picture attached to post). A few AMD cards need a different Dremel mod. Check the GPU tables for details.

Q: Is there is a single optimal card?

No! Your iMac model, your budget, your comfort level with doing modifications, your ability to live with unresolved issues, your computing needs, the local market, etc. will determine the card to be used.

Q: Where do I get a card?

Unfortunately, this thread cannot help you source cards as there are too many variables involved. Do not post online offers, these are out of date the moment you publish it.

Q: Is there a most feature rich card?

There is a feature rich card - the AMD WX4130. But it will work in eDP (see table below) iMacs without modification using the EFI or GOP vBIOS. Like other GCN4 cards this model offers DRM, 4K HEVC, 4K H.265, VideoToolbox, and native macOS Monterey support. Still usable with patches on Ventura.

Q: What are the most future proof cards?

AMD GCN4 and AMD RX 5500 XT cards - the latter lacks Ventura support.

Q: Is there a card which will fit in all iMac models?

There is a most compatible card, the M4000/M5100/W5170M. It can run in any iMac listed below offering an EFI boot screen with the correct vBIOS flashed. Unfortunaly eDP and LVDS type iMacs need different vBIOS versions.

Q: Are there incompatible combinations of cards an iMacs?

Yes, there are! But there is a most compatible receiver, the iMac11,3 27, which can run literally every card tested, listed, or mentioned on the thread (iMac11,1 is compatibly in the same way). For all other iMacs you have to read and work through this entire page.

Read through this information carefully in order to choose the best card for your needs.

Q: Which iMac models can be upgraded?

System support table:

card/system familyiMac9,1 24iMac10,1 21.5iMac10,1 27iMac11,1iMac11,2iMac11,3iMac12,1iMac12,2
connector typeLVDSLVDSeDPeDPeDPeDPeDPeDP
NVIDIA (EFI)nononoyesyesyesyesyes
AMD (GOP)yesyesyesyesyesyesyesyes
AMD EG2 (EFI)nononoyesyesyesyesyes
AMD EG (EFI)yesyesyesyesyesyesyesyes

  • NVIDIA (EFI): EFI boot screen support, press alt/option on boot, Windows EFI/UEFI support, only eDP
  • GOP: OpenCore for emulated boot picker (press ESC on boot, not alt/option), Windows UEFI support
  • AMD EG2: EFI Boot screen support with iMac EG2 firmware modification, limited Windows UEFI support
  • AMD EG: EFI Boot screen using the EnableGop driver enhancing GOP, Windows EFI/UEFI support
Q: What does GOP and EFI mean at all?

GOP is an UEFI2.0 driver found in any properly flashed post 2012 graphics cards. Our iMacs uses EFI 1.1 drivers to provide the well known Apple EFI boot screen. The GOP driver - on the other hand - will provide an emulated boot picker (press ESC on boot, not alt/option) when using OpenCore boot loader and it provides Windows 10/11 UEFI driver support.

Since Apple owners are used to the EFI boot picker we developed drivers to support the EFI picker. All NVIDIA vBIOS have an EFI driver included, for AMD we have two different developments named EG2 and EG. We recommend using the EG version.

Q: What is the difference between AMD and NVIDIA cards?

AMD cards have better macOS support, in particular on Monterey and later and there is at least a single model for every MXM3 iMacs available. AMD GCN1-3 need 10.10, AMD GCN4 need 10.12 and Navi cards need 10.15 minimum to get macOS driver support.

NVIDIA cards lost support with Monterey. Patching with Ventura became more and more difficult, expect to only limited support with Ventura and later macOS versions. Do not fall for old over priced 8GB cards just to run Big Sur. But you can run older macOS versions back to 10.8.3 using a NVIDIA card. You cannot use NVIDIA properly in LVDS iMacs (no EFI boot screen support).

Q: What is about other MXM3 cards?

Post High Sierra macOS support is limited to NVIDA Kepler GPU and AMD GPU from 2012+ (GCN1-4, RDNA), therefore we do not discuss the use of Maxwell or Pascal cards here, although these run perfectly with High Sierra, Windows, and Linux. Check this thread to get more information.

If this information is not really clear ask about support and experiences with older iMacs or search this thread.

This is a single interesting option to re-use an hp AMD Radeon HD6770M laptop card and use it in iMacs flashing the correct vBIOS. No metal support but you can just prolong the live out your iMac running older macOS versions up to High Sierra!

All details about LVDS support can be found in this post. Please also read this post to understand how to setup OpenCore through OLCP in advance to boot macOS properly.

All EFI vBIOS version can be found on this external Github repository. Since there are similar cards with different VRAM, please download the version matching your card.

There are different versions for iMac10,1 (EnableGop-LVDS) and iMac9,1 (EnableGop91-LVDS) - please check carefully which version you need.

The bigger MXM-B cards will only fit into the 24" iMac9,1 with GT130 or ATI 4850 card. This GPU generation named GCN1-3 need macOS 10.10 minimum.

There is a hardware hack for the iMac9,1 to connect the internal LCD with a display driver board, rerouting the connector trough the memory door to the miniDP port. This makes the internal panel working as an external one and thus supports more recent GCN4 and NVIDIA cards - but without any brightness control.

One user reported the internal LCD would work after letting the system sleep. Some cards may work with the stock BIOS and OpenCore boot picker showing all/some of the seven problems.


CardBIOSBoot ScreenBrightness Control21.5/24/MXMHeat Sink ModOGLMET
Venus family:
AMD M4000BIOSyes (EFI)yes (natively)yes/yes/Ano, special install80919
AMD M6000BIOSyes (EFI)yes (natively)no/yes/B24 iMac9,1 only101030
AMD M5100BIOSyes (EFI)yes (natively)yes/yes/Ano, special install98331
AMD W5170MBIOSyes (EFI)yes (natively)yes/yes/Ano, special install93230
AMD M6100BIOSyes (EFI)yes (natively)no/yes/B24 iMac9,1 only130045
AMD W6170MBIOSyes (EFI)yes (natively)no/yes/B24 iMac9,1 only150045

The W6170M overheats the iMac9,1 on long Valley or gaming runs. So it is a working option unless you are abusing it. The older C2D CPU limits OpenGL test results while metal results remain the same.

Sleep and wake, and cold boot is broken in iMac12,x 2011 system. Needs a PRAM reset on each cold boot - DO NOT USE IN 2011 iMac12,x systems. This problem does not depend on the BIOS in use, so even with an EFI BIOS the very same problems will show up!

Fully supported on iMac10,1 27 and all iMac11,x (EG, EG2, GOP)!


This GPU generation named GCN1-3 need macOS 10.10 minimum.

Please read the known issues section first!

- most cards cause a crash on wake on iMac12,x systems (disable sleep) or severe NVRAM corruption on cold boot needing one or more PRAM reset to start properly. It is not a great idea to use such a card in the iMac12,x systems. A few cases were reported with working cards, in all cases the old 3.5 inch HDD was still in use. This device may cause some delays in the power on and wake process avoiding the GPU to fail (aka wake successfully).
- you need OpenCore (OCLP 0.4.0 and later) to setup and run those + cards, no EFI boot picker available
- check the vBIOS links for more details and compare OCLP generated config.plist with the settings there in case to trouble
- some cards cause additional SMBUS address problems (W6170M, W5170M), CPU thermal readings are partly broken (hardware issue, needs modding the card)
- W5170M does not run properly in the iMac11,2 (hardware issue, needs modding the card), use Dell M5100 instead
- W6170M/W7170M/S7100X do not run properly in iMac12,2, please do not try unless you want to develop/explore a solution for the NVRAM corruption problems and failing start/reboot/boot problems happening on this machine
- VRAM support may not be complete, we have already created some special versions. So please visually check your own card and read the print on the VRAM chips to get the correct version to flash! Using the wrong vBIOS may brick your card and would need a clip to recover.
- GOP vBIOS version have problems to work/sync with external displays. sync needs display sleep, press SHIFT+CRTL+EJECT and wake the iMac up again.
- all MXM-B cards need a heat sink mod with a Dremel

All EFI vBIOS version can be found on the external Github repository. Since there are similar cards with different VRAM, please download the version matching your card.

Nearly all GOP vBIOS version can be found on the same repository.

CardBIOS
GOP
Boot ScreenBrightness Control21.5/27/MXMHeat Sink ModOGLMET
Venus family:
AMD M4000GOPyes (EFI)yes (natively)yes/yes/Ano, special install80919
AMD M6000GOPyes (EFI)yes (natively)no/yes/Byes, 2 pipe MXM-B101030
AMD M5100GOPyes (EFI)yes (natively)yes/yes/Ano, special install98331
AMD W5170MGOPyes (EFI)yes (natively)yes/yes/Ano, special install93231
Saturn family:
AMD M6100GOP
ROM2
yes (EFI)yes (natively)no/yes/Byes, 2 pipe MXM-B102430
AMD W6170MGOPyes (EFI)yes (natively)no/yes/Byes, 3 pipe special install180557
AMD W6150M & E8870GOP
ROM2
yes (EFI)yes (natively)no/yes/Byes, 3 pipe special install
Tonga family:
AMD W7170MGOPyes (EFI)yes (natively)no/yes/Byes, 3 pipe
AMD S7100XROM
ROM2
yes (EFI)no (hw mod needed)no/yes/Byes, 3 pipe181286

OGL column: OpenGL performance based on the Unigine Valley score from this table.
MET column: Metal performance based on MetalBench score from the table.
Heat Sink Mod AMD MXM-B: Take a look at this post - and these cards do not fit in smaller 21.5 models

EFI vBIOS:
All version can be found on the external Github repository. Since there are similar cards with different VRAM, please download the version matching your card.

DRM and AirPlay:
- all cards support AirPlay to AppleTV with Catalina on all iMac11,x and iMac12,2 using OpenCore (Lilu/WhateverGreen)
- all cards seem to support AirPlay to Mac with Monterey and Ventura (OC)
- all cards support DRM AppleTV on all macOS version including Ventura (Saturn needs a DeviceProperties edit, add enable-gva-support of type integer with value 1 side by side with agdpmod entry with OLCP 0.4.11 and older)

Windows 10:
Installing W10 in UEFI mode is compatible with OpenCore (unlike BootCamp legacy Windows). Using GOP/EnableGOP vBIOS will boot Windows. A few cards show the infamous error 43 in the DeviceManager. One can get around this (not tested with all cards) using the driver signature patch as described on the page. Rename the tool and run as (Windows) admin and reboot. @nikey22 posted a nice recipe how to adjust Windows driver support.

Please read the issues section first! These cards have been introduced 2016 and later and are considered as new cards. The GPU type is more power efficient compared to Nvidia Kepler and has by far higher metal performance.
This GPU generation named GCN4 need macOS 10.12 Sierra minimum.

General: Some AMD cards will not POST (Power On Self Test) and will not run in the 27" Mid 2011. This happened with some WX7100 models, all RX480, some HP AMD cards.
  1. AMD WX7100 (mobile)
    Cards with a version number of 1.1 (search for a print on the front side of the card like V1.1 or VER 1.1) will work in all 27" iMac Late 2009- Mid 2011 while the version 1.0 will only run in Late 2009 and Mid 2010.
  2. RX480 and RX470 (mobile)
    RX470/RX480 cards are version 1.0 only - and do not work in Mid 2011 iMac systems!
  3. AMD WX4170 (mobile)
    Some come with a blank EEPROM and are missing a resistor network. Working models with EEPROM are scarce. You can add a BIOS chip following this post. It requires soldering skills (ask cell phone repair shops)!
  4. AMD WX4130/WX4150 (mobile)
    There are multiple versions of this card - only the green "Dell" branded versions currently work in every supported iMac model except the iMac11.2. Other cards like the blue HP WX4150 needs this mod to work in the 2011 iMac12,2 27 inch models. The Dell and HP cards need this additional mod to work in the iMac11,2 and iMac12,1 21.5 inch models. Check your card before applying any mod.
  5. Initial setup: Using High Sierra the GOP vBIOS disables the internal LCD on power on.
    Work around: Use an additional external display.
    If you plan to use High Sierra on a regular basis you can just use a miniDP emulator stick (recommended) or you can implement this hard wire mod (only mentioned here to have a complete overview) or patch it or you can enable the OpenCore agpdmod=vit9696 in the boot-args. Unfortunately this setting is not always compatible with more recent macOS versions and may break access to external displays. Patching is the most easy way.
  6. RX480 EFI: Limited UEFI Windows support. The EFI picker needs a specific subsystem ID which breaks automatic driver detection in Windows. You may have success with manual driver installation using the device driver assistant.

All EFI vBIOS version can be found on the external Github repository. Since there are similar cards with different VRAM, please download the version matching your card.

CardBIOS
GOP
Boot ScreenBrightness Control21.5/27/MXMHeat Sink ModOGLMET
AMD WX3200
*
GOPyes (OC and EFI)yes (natively)yes/yes/Ano, special install175349
AMD WX4130 **GOPyes (EFI)yes (natively)yes/yes/Ano, special install180553
AMD WX4150 **GOPyes (EFI)yes (natively)yes/yes/Ano, special install180562
AMD WX4170 **GOPyes (EFI)yes (natively)no/yes/Bno, special install215673
AMD RX470 **GOPyes (EFI)yes (natively)no/yes/Bno, 3 pipe 20112700145
AMD RX480 **GOPyes (EFI)yes (natively)no/yes/Bno, 3 pipe 20112800150
AMD WX7100 **GOPyes (EFI)yes (natively)no/yes/Bno, 3 pipe 20112949170

OGL column: OpenGL performance based on the Unigine Valley score from this table. T
MET column: Metal performance based on MetalBench score from the table.

** These AMD cards are much more modern, but are difficult to source. Check the online offers carefully (the differences are explained above). The cards are be supported natively with Sierra and later. Latest known working macOS version is currently Monterey. Partial support on Ventura. 2/6/24 UPDATE : WX4130 is working solidly with Sonoma on 12,2 ( link )
* The AMD WX3200 uses a simple Lexa GPU core, supported by macOS using a spoofing trick. It does not offer VA (needed for FinalCut and DaVince and similar) but DRM support. At a similar price the WX4130 is possibly a better choice. The card is relatively new from 2019.

EFI vBIOS:
All version can be found on the external Github repository. Since there are similar cards with different VRAM, please download the version matching your card.
OpenCore:

Using the GOP/EG2 BIOS (links within the table above) you will have native brightness and and get an emulated boot selection only with OpenCore (see below). OpenCore enables 4K H.264, and huge 4K HEVC decode/encode by using the iMacPro1,1 ID. This hack makes your iMac look alike a new machine and gives you similar features. Does not work with Sierra when using OpenCore (add the -no_compat_check to boot-args to enable booting Sierra).

Windows 10:
Installing W10 in UEFI mode is compatible with OpenCore (unlike BootCamp legacy Windows). Using GOP/EnableGOP vBIOS will boot Windows. A few cards show the infamous error 43 in the DeviceManager. One can get around this (not tested with all cards) using the driver signature patch as described on the page. Rename the tool and run as (Windows) admin and reboot.

How to flash:
Cards can be flashed using a clip or amdvbflash with Linux or Windows or EFI. Take a look at the FAQ Q3 about flashing cards.

AirPlay and DRM:
AirPlay to Mac works with these cards installed on Monterey and Ventura!
AirPlay to AppleTV in general with Mojave and Catalina. Big Sur and later broke this.
DRM works with all cards.

Lately some used RX 5500 XT MXM dGPU models were available in China built for crypto mining back in 2019/2020.
Additionally Sonnet used different models (MXM non standard size) in their eGPU offerings.
You find preliminary results with such a Sonnet RX 5500 XT AMD Navi GPU in iMac11,3. There is also a RX5700XT version of the Sonnet Puck, possibly one can find such a card in a few months cheaply on eBay...
A full report about the cards from China can be found on the post following the ROM link below in the table.
All EFI vBIOS version can be found on the external Github repository. Since there are often card with different VRAM please pick the version matching your card.

This GPU generation named NAVI need macOS 10.15.5 Catalina minimum.

CardBIOSBoot ScreenBrightness Control21.5/27/MXMHeat Sink ModOGLMET
RDNA 1:
RX5700XTyes (OpenCore)no/yes/A3 pipe
Navi 14:
RX5500XTROMyes (OpenCore / EFI)yes (OpenCore / HW)no/yes/Babsolutely! 3 pipe2729233

The China RX5500XT is the ultimative GPU to be used in iMac12,2 systems. It offers support for at least two external display and highest performance ever measured here.

Valley results were really similar regardless which resolution and quality I picked ( 2560x1440, normal 2455, ultra 2066 ) and (1920x1080 normal 2729, high 2371, ultra 2396). This is surely different from all other cards we ever had tested.

Please read the issues section first! Most of these cards hit the street 2012 and are considered as old cards. Optimal for macOS up to Big Sur, some non fixed issues on Monterey, serious problems with Ventura 13.3+. If you plan to use Ventura do not buy a Kepler card these days!

  1. EFI Boot screen support on iMac11,x and iMac12,x systems, only.
  2. HP cards may have no vBIOS installed and do not boot installed in your iMac at all - so you may need to clip flash these cards in advance. Cards without a vBIOS may prevent booting.
  3. Dead old cards: Cards were released in 2012/2013 and may be already (half) dead. Some sellers offer cards with new BIOS - but to small - chips soldered on. Ignore those offers. If you cannot get video output working on internal and/or external displays face the bitter truth: The card may be DOA (dead on arrival). We are not a support organisation. Get your card returned and please do not waste (your and our) time on it!
  4. iMac 2011 SMBUS bus problems: Some NVIDIA GPU may not run in your 27 Mid 2011 iMac. We have reports of GTX880M, K3000M, K3100M, K4100M, K5000M which all run only without the internal LCD connected. As soon as you connect the LCD the system refuses to boot or ends up in boot chime loop. The same error can be caused by connecting a new internal SSD. Root cause may be an address conflict on the SMBUS caused either by the GPU or some IC on the card connected to the SMBUS delivering thermal date. One can visualize such problems with tools like HW Monitor. If you find weird (CPU, environmental) temperature readings (129C) you might have such a card. Hardware solution: Try this modification.
  5. sleep/wake broken: In a few cases even on iMac11,1 and on iMac12,2 with some NVIDIA cards sleep/wake is broken with an error message like Sleep Wake Failure in EFI - neither root cause nor a fix is known. No developer can fix a problem he himself has never seen or which cannot be forced or reproduced in a consistent way. Disable system sleep!
  6. Video Memory type: NVIDIA and AMD cards can have different VRAM memory types (Hynix AFR, Hynix BFR, Elpida, Samsung). Take a look at the links within the tables to find your fitting BIOS. For some cards - although listed below - we may not have the correct memory versions prepared. Flashing the incorrect vBIOS can brick your card and may need clip flashing - which is not possible for most NVIDIA cards.
  7. Black Screen: After a PRAM reset the LCD gets and remains black. Just press alt/option on boot to force the EFI boot screen, this enables the LCD. Unfortunately this does not work on iMac11,1 and you need to apply one of the the fixes below:
    - Sierra, High Sierra, Mojave, Catalina: Use this package installer to solve this issue with all NVIDIA cards on all systems up to macOS Catalina. Do not use this package on Big Sur and later.
    - Big Sur and later: Install OCLP or manually add with agdpmod=vit9696 in the boot-args in OpenCore. This fires up the LCD even after a PRAM reset or GPU change, too.
  8. Color depth problem: Happens on every boot - just sent the system once to sleep or change resolution. This solution or this opencore based solution may cure the problem.
  9. Brighness level: Solution is linked here for all ++ cards and described by @nikey22 on each of his posts, again. Included in OCLP by default.
  10. Brightness control with OpenCore: All + cards need OCLP or CL to enable brightness control. OCLP solves the issue #7 at the same time: win-win!

CardBIOSBIOSBoot ScreenBrightness Control21.5/27/MXMHeat Sink ModOGLMET
Quadro K610M *ROMyes (EFI)yes (OC, issue 7 )yes/yes/Aspecial install505n/a
Quadro K1100M *ROMElpidayes (EFI)yes (OC, issue 7 )yes/yes/Ano907n/a
Quadro K2100M *ROMElpidayes (EFI)yes (OC, issue 7)yes/yes/Ano1229n/a
Quadro K1000M *ROMnoBCyes (EFI)yes (OC, issue 7)yes/yes/Ano903n/a
Quadro K2000M *ROMnoBCyes (EFI)yes (OC issue 6)yes/yes/Ano797n/a
Quadro K3000M **ROMROM1yes (EFI)yes (issue 6 above)no/yes/Byes, 3 pipe116415
Quadro K4000M **ROMyes (EFI)yes (issue 6 above)no/yes/Byes, 3 pipe1680n/a
Quadro K3100M **ROMROM1
ROM2
yes (EFI)yes (issue 6 above)no/yes/Byes, 3 pipe177921
Quadro K4100M **ROMyes (EFI)yes (issue 6 above)no/yes/Byes, 3 pipe246532
Quadro K5000M **ROMROM1yes (EFI)yes (issue 6 above)no/yes/Byes, 3 pipe203829
Quadro K5100M **ROMyes (EFI)yes (issue 6 above)no/yes/Byes, 3 pipe2404n/a
GTX 680M **ROMyes (EFI)yes (issue 6 above)no/yes/Byes, 3 pipen/an/a
GTX 765M *ROMyes (EFI)yes (issue 7 above)no/yes/Byes, 3 pipe1428n/a
GTX 770M *ROMyes (EFI)yes (issue 7 above)no/yes/Byes, 3 pipe2140n/a
GTX 780M *ROMyes (EFI)yes (issue 7 above)no/yes/Byes, 3 pipe264241
GTX 780M **ROMyes (EFI)yes (issue 7 above)no/yes/Byes, 3 pipe264241
GTX 880M **ROMyes (EFI)yes (issue 7 above)no/yes/Byes, 3 pipe2700n/a
GTX 860M **ROMyes (EFI)yes (issue 7 above)no/yes/Byes, 3 pipe161634
GTX 870M **ROMROM1yes (EFI)yes (issue 7 above)no/yes/Byes, 3 pipe232640

OGL column: OpenGL performance based on the Unigine Valley score from this table.
MET column: Metal performance based on MetalBench score from the table.
OC: OpenCore by OCLP
Heat Sink Mod NIVIDA MXM-B: Take a look at the attached pictures to this post!

*
BIOS by @Nick [D]vB, @nikey22, and @Santa's Little Helper that currently enable boot screens on your iMac.

Using OpenCore (through OLCP or Catalina Loader for High Sierra and Sierra) these cards offers right now native brightness control, target display mode, support of UEFI Windows 10, and more!

**
BIOS by @nikey22, and @stephle that currently enable boot screens, native brightness control, target display mode.

Notes:
  1. Most if not all of these cards have a WSON type BIOS chip which cannot be programmed using a clip. You need nvflash with Windows or Linux. Take a look at the FAQ Q3 about flashing cards.
  2. Audio support with UEFI Windows 10 needs OCLP (OpenCore)
  3. To enable brightness controls in UEFI Windows 10, see this post and this more recent post.
  4. Target Dispay mode works only with High Sierra an older, but check this post.
  5. All cards offer native EFI boot screen support!

Regularly we get the requests about the more modern Nvidia Pascal and Maxwell GPU cards. Unfortunately Apple never supported these cards on more recent macOS versions. In case you plan to use such a GPU you will have to install the so called NVIDIA web drivers to get High Sierra support.

On the other hand these GPU are perfectly able to run Windows and likely some Linux distribution with full driver support. So if your focus is Windows only take a look at this great and growing offspring thread.

You will find special vBIOS versions searching this not so long thread, but rapidly growing thread!

You will find a short but hopefully comprehensive plan of the complete process in this post #14897. It included also a tools section.

The repair site ifixit.com offers step by step repair guides for each model we cover on this thread. For example check these 27 iMac12,2 and 27 iMac11,x and 21.5 iMac11,2 out. There are separate guides for the GPU upgrade as well as every other repair and upgrade possible.

There are countless videos about the hardware upgrade process available online, this great video is short, complete and entertaining at the same time. It covers the iMac12,1 21.5 inch model. You will find videos about other models easily.

Important:

Simply do not use
the @dosdude1 patcher with any iMac9,1 and iMac10,x or iMac11,x model!

You have a single patcher option for all new macOS versions based on integration work of @Ausdauersportler into the tool provided by @khronokernel and @dhinakg! It can be used to install Ventura, Monterey, Big Sur as well as Mojave and Catalina. After installing OpenCore your system will be qualified to run the stock installer programs provided by Apple.
  • OCLP (this package offers a recent OpenCore package and enables installation of most recent macOS versions)
We recommend all new users to use OCLP. First read the documentation linked on the download page.

OCLP is by far superior and one and only supported solution on this thread, no exception! You can even (ab)use OCLP to enable Sierra and High Sierra support on iMac9,1 systems. No patching aka altering the Apple installation is needed.

OpenCore (OC) is a boot loader software to enable some features and to provide necessary data before an unsupported or supported macOS boots. Normally it takes a lot of effort to configure this software correctly, but using the OCLP tool (OpenCore Legacy Patcher) generating automatically a tailored configuration and offering macOS installation and patching support you get all at once. Please study the online docs provided. OpenCore is installed using this OCLP app to the hidden EFI partition of your main internal disk.

Using an AMD dGPU you can enable Apple silicon features within the Apple Macs app using this Lilu plugin named AdvancedMap. Instructions can be found in this post.

Normally you use the EFI boot picker to control the boot sequence. Unfortunately using a metal GPU with a GOP vBIOS offers no EFI Boot screen! OpenCore in turn closes this gap and offers an emulated boot picker for those cases. Warning: Changing the OpenCore config manually may leave your system unbootable.

In general all iMac systems listed can have an EFI picker with nearly all AMD cards using the EnableGop vBIOS versions from this external repository. But in case you are using a GOP vBIOS you may find this recipe still useful:

@cdf described how to create a OpenCore Recovery CD. You can create such a CD in advance or using OLCP even on a different machine even after loosing a working internal OpenCore installation. Follow the guide from this thread (Maintainance->Creating a rescue CD). Follow the instructions to the letter. It needs manual editing of the OCLP generated config.plist file.You can either use the OCLP config of your iMac or start the OCLP app to generate and copy files from the temp. folder OLCP uses.

After a PRAM reset you can force booting the CD pressing the C button on power on.

  1. Native and unpatched installation of Mojave, Catalina and Big Sur, patched for Monterey and Ventura with OpenCore Legacy Patcher (OCLP)
  2. Brightness control with K610M, K1100M, K2100M, K1000M, K2000M, GTX765M, and GTX770M cards
  3. Emulated boot picker for new graphics cards having no working EFI vBIOS!
  4. WINDOWS 10 UEFI installations on Mid 2011 sound patch
  5. AMD Video acceleration 4K HEVC and 4K H.264 for GCN4 and Navi cards
  6. OTA (over the air) Apple software upgrade on Monterey, Big Sur, Catalina, and Mojave.
  7. AMD DRM (HW support) for Netflix (even in Safari), AppleTV, Amazon Prime etc. streaming (all AMD GCN1-GCN4)
  8. solves black screen issue with all NVIDIA GPU (using agdpmod=vit9696 in boot-args)

Thread: Manually Configured OpenCore on the Mac Pro (if you really want to understand how to utilize OpenCore on Macs, latest macOS supported is Monterey)
Thread: Activate AMD hardware acceleration (out of date, cannot catch up with Ventura and Sonoma like OLCP)
Videos: How to maintain OpenCore
Full OpenCore Legacy Patcher documentation
Full OpenCore documentation

Catalina Loader (CL) was another solution based on OpenCore to be installed on USB or SD devices and maintained more easily on visible file systems than on hidden EFI partitions. The solution was helpful in times without an EFI boot picker. Since we now fully support EFI boot with all AMD cards there is no need for this out of date solution.

Download: Catalina Loader image and original OC version
Post: The original OpenCore post on this thread
Guide: Guide by @Herrdude
Guide: Using Catalina Loader on an iMac

1. UEFI

OpenCore up to version 0.9.4 could only boot UEFI installations. Legacy installations never showed up in the OC boot picker. Therefore installing Windows in UEFI mode was the best solution. Lately OpenCore 0.9.5 added a new driver (OpenLegacyBoot) which make your EFI Windows installation appear on the picker and let you boot it through OpenCore, too. OCLP has adopted and included this driver by default.

The best recipe to install UEFI Windows is maintained in this thread within the OpenCore configuration guide. A similar guide has been included recently into the OCLP documentation on this page. It covers the EFI management and also the iMac12,x Windows HD3000 issue. OpenCore will also enable the sound on 2011 systems using UEFI Windows.

2. Legacy / EFI

Our iMacs are pre-UEFI systems, therefore Apple supported only this installation method using the BootCamp utility.
@nikey22 has provided a great step by step guide how to install legacy Windows on iMacs with upgrade GPUs.

3. General notes

In case you lost your Windows EFI boot entry accidentally after installing OCLP take a look at this post how to recover it. Best way to avoid this is creating a 2nd 200MB FAT16 partition to save OpenCore.

Using AMD GOP vBIOS you may get the famous error 43 when loading the Windows AMD driver. There is a recipe to patch out the driver signature check. Download the binary, rename it as described in the description and run as administrator. After rebooting the AMD card should run perfectly accelerated (worked with my RX480 in the iMac11,3 recently).

Apparently the Apple firmware of all 2009 iMacs prevents Windows brightness control to work (works on all newer 2010 and 2011 iMac models).

According to this list the (Kepler) Nvidia drivers are part of macOS since 10.8.3.
According to this GPU buyers guide the new AMD GCN4 will be supported with macOS Sierra and later
The older AMD GCN1-3 GPU need 10.10. Navi GPU need 10.15.

Supported MacOS version can be installed using the original Apple installer. To avoid the black screen issue install this package.
Only the iMac9,1 does not support Sierra natively and would need OCLP installing OpenCore with moderate spoofing enabled using the iMacPro1,1 SMBIOS - this way you can boot OpenCore and install Sierra.

Since OCLP fixes NVIDIA brightness issues and enables DRM on GCN1-4 and 4K HEVC/H.264 support on GCN4+ you should install and OpenCore even when running Sierra.

Supported MacOS version can be installed using the original Apple installer. To avoid the black screen issue with NVIDIA cards install this package. To avoid APFS preboot corruption of other Big Sur or Monterey installation use HFS+ for High Sierra!!

Installing this last supported macOS version brings in the latest firmware. There will be unlikely ever new firmware versions since High Sierra went out of Apple support in Summer 2020.

Using an AMD GPU you need to install OpenCore using the latest OCLP. This way you can use all the superior functionality of the AMD GPU and avoid any possible problems like sleep/wake issues! Possibly one needs the agdpmod=vit9696 boot-args entry to enable the internal screen with AMD Polaris/Ellesmere cards on High Sierra using OCLP, this does not apply to GCN cards!

Only the iMac9,1 does not support High Sierra natively and would need OCLP installing OpenCore with moderate spoofing enabled using the iMacPro1,1 SMBIOS - this way you can boot OpenCore and install High Sierra. To update High Sierra use simply the 2020 security upgrade package.

Since OCLP fixes NVIDIA brightness issues and enables DRM on GCN1-4 and 4K HEVC/H.264 support on GCN4+ you should install and OpenCore even when running Sierra.

About double booting with High Sierra:

High Sierra uses APFS but starting it up will corrupt the preboot partition in a way it badly interferes with Big Sur and later. If you need a double boot consider using Sierra instead on HFS+ in a separate partition!

Using OCLP is the only supported installation method on any iMac9,1, iMac10,1, iMac11,x and on iMac12,x using metal AMD GPU.
The OCLP patcher GUI app will auto detect your system, BT, WiFi card and GPU. Carefully check in Build OpenCore step if everything has been detected properly. It generates a config specifically for your particular system and your GPU. You cannot use the config on other different iMacs! First install the new GPU, than install OCLP!

Having a Metal GPU makes your iMac Late 2009, Mid 2010, Mid 2011 fully compatible, again. All necessary WiFi, Ethernet, Sound, BT drivers will be injected using OCLP. OLCP is designed to support Big Sur and later, but works like a charm with older macOS versions when using settings as described below:

If you plan to use/install Sierra or High Sierra or Mojave or Catalina using OCLP enter the Patcher Settings and
  1. set SMBIOS Mode->moderate
  2. disable Securebootmodel by SBM->False
  3. disable SIP with setting SIP->False
This is method is not exactly intended or supported by the OCLP dev team but it works like a charm.

Reboot, press alt/option and select the OpenCore on boot. Make it default by pressing CRTL.

Known Issues/Features with Catalina:
  • OTA update with OpenCore will only work if your are using the VMM flags as needed for Catalina described here (needs config.plist editing!!) or with moderate spoofing! You can return to minimal spoofing and default OCLP settings after installing the last 2022 Catalina security update. There will be no more updates. Similar applies to Mojave and the 2021 security update.
  • OCLP 0.2.5 and later changed to shikigva=128, Catalina needs 80 to have working DRM. Go back to 0.2.4 or manually edit the config.plist when using later versions.
  • AirPlay will work with every listed AMD dGPU on Mojave and on Catalina using the original Atheros WiFI card.

This installation method is only necessary on iMac12,1 and iMac12,2 systems equipped with NVIDIA cards. It enables HD3000 iGPU support and AirPlay. Only 2011 iMac12,x have HD3000 type iGPU!
This is a legacy patching instruction. We strongly recommend to use OCLP to install macOS Mojave or later. This section is only important for users of Mid 2011 systems with an NVIDIA card needing Intel QuickSync (H.264 encoding) to work.

AMD users will use the AMD GPU superior H.264 encoding and do not need Intel QuickSync. So an AMD user will never need to install using this method and have to use OCLP! Older iMacs do not have QuickSync hardware support and cannot use it therefore.

This is a two step installation. First you will use the @dosdude1 patcher and later install a package needed to address the hardware changes you made by changing the GPU.

1. You could preinstall Mojave before changing your GPU. Use dosdude1's Mojave patcher to do the install.

Important: While running the Post Install tool, make sure you deselect the Legacy Video Card patch option (since you will using a new, compatible metal graphics card).

2. GPU and machine related patches: (see next section common macOS problems)
Mid 2011: Simply install this package to avoid sleep problems, black screen etc. or follow this post.

Important: Post-install patching has changed since Mojave.
Patching is automated if your SMBIOS is detected to be an unsupported machine. Currently, only the 2011 iMacs have the "Legacy Video Card Patch" disabled by default. iMac11,x user should use OCLP to install Mojave or Catalina in any case!

Important: While running the Post Install tool, make sure you deselect the Legacy Video Card patch option (since you will using a new, compatible metal graphics card).

The process for Catalina is similar to Mojave as mentioned above. Use dosdude1's Catalina patcher to do the installation. Catalina lost support in summer 2022, there will be no more updates.

1. Since Apple softwareupdate is broken on Catalina the best way to install Catalina is using OCLP as described before. Use the dosdude1 patched USB installer to put OLCP (moderate spoofing) onto it and boot the USB! It will allow you to start the Catalina installer and update using OTA.

2. After finishing the installation and after applying all OTA updates boot the dosdude1 patched installer and apply the dosdude1 patches only a single time! Since no more Catalina updates will be published and dosdude1 will unlikely update his patchers you can also avoid installing the patch updater (de-select this option).

3. Finally install this package to avoid iMac 2011 sleep problems, black screen etc. (easy way).
Alternatively follow this post for AirPlay/sleep&wake and this post to enable this display ports manually.

Please discuss all experiences on this thread: macOS 11 Big Sur on Unsupported Macs

Known Issues/Features with Big Sur 11.6+:
  • iGPU based H.264 QuickSync is broken, no more AirPlay using an NVIDIA GPU with OCLP.
  • Airplay to AppleTV is broken with AMD dGPU, too (needs BT/WiFi update, regardless which other hardware the best you can get is sound output, screen remains black)
  • using Big Sur/Monterey and High Sierra on APFS on the same machine can corrupt the Big Sur/Monterey preboot volume and prevent it from booting properly. Take a look and this post for a solution. You will disable the mount of the Big Sur volumes when starting High Sierra. The best approach is using High Sierra on an HFS+ partition!
  • Using a AMD cards on Big Sur may break screen recording (use a third party app). Fix is using this command defaults write com.apple.cmio CMIO_Unit_Input_ASC.DoNotUseOpenCL -bool true
  • Using new AirPods and HomePods needs BT/WiFi update
  • The stock Atheros WiFi and old BT are supported by OLCP and. No HandOff and no Continuity, of course.
  • DRM is working, Apple TV will show movies online, Netflix (currently not in Safari), Amazon Prime and others should work, too. This is valid even with High Sierra, Mojave, Catalina booted through OpenCore (all AMD cards, W6170M need OCLP 0.5.0+).
  • reverting root patches does not work on Big Sur (Apple APFS bug, never fixed)! In case you need to change patches after installing a new metal GPU or the BT/WiFi upgrade you need to re-install Big Sur on top of the existing installation (will preserve user data).
Notes
  1. OCLP can be used without any patching and if offers SIP, File Vault and most importantly OTA delta upgrades. No other tool can offer this! Kepler needs patching with Monterey and later. All iMacs need root patching on Ventura!

Please discuss all experiences on this thread: macOS 12 Monterey on Unsupported Macs

Known Issues/Features with Monterey 12.5+:
  • Kepler support has been broken in Monterey 12.5
    solution: use OCLP 0.5.0 or 0.6.8 an later for Monterey, root patches are needed now. No more delta upgrade after patching.
  • Best OCLP version for AMD iMacs is 0.4.11 - there is no need to update the OpenCore boot loader unless you want to install Ventura and later
  • on Monterey all old BT devices stopped working!
    solution: hardware upgrade with BCM94360CD or similar (HandOff, Continuity)
    solution: use latest OCLP 0.4.5+ with BT fixes
  • on Monterey all old WiFi devices stopped working!
    solution: hardware upgrade with BCM94360CD or similar (HandOff, Continuity)
    solution: use latest OCLP 0.4.5+ and apply WiFi post install patches
  • UC works on iMac12,x only and needs hardware BT/WiFi upgrade
  • AirPlay to Mac needs hardware BT/WiFi upgrade and works on iMac12,x with AMD GCN 4 dGPU, only (AFIAK)
  • Using new AirPods and HomePods needs hardware BT/WiFi upgrade
  • TM restore and MA (migrations assistant) is broken on root patched systems. So please use both tools before patches will be applied or revert patches, perform your restore, and apply patches later.
  • Using a AMD cards on Monterey may break screen recording (use a third party app). Fix is using this command defaults write com.apple.cmio CMIO_Unit_Input_ASC.DoNotUseOpenCL -bool true - works still on Monterey 12.7.3 with Navi and GCN4 cards installed.
Notes
  1. OCLP can be used without any patching and if offers SIP, File Vault and most importantly OTA delta upgrades with AMD dGPU and BT/WiFi upgrade. Both Kepler and stock BT/WiFi needs root patching, only full size upgrades when using Apple software update process as usual. No other tool can offer this!

Ventura and later needs an AVX2 capable late 2013 Intel CPU to run macOS properly. One can circumvent this with a lot of patching done in particular with AMD graphics driver and OpenGL and OpenCL drivers. This kind of patching will never be 100% perfect. As time goes by the problems will become more and more visible and at some point in time not any longer patchable.

The latest OCLP supporting Ventura and Sonoma is a technical masterpiece, you cannot compare it's functionality with former versions. A lot of behind the scenes magic is happening in order to allow Ventura booting even on unsupported pre AVX2 CPUs and systems.

Kepler support becomes difficult to sustain. Please always read the change log of OCLP before updating macOS. But perfect support is difficult to achieve and keep alive. Kepler uses the 3802 metal compiler, which has been ripped from Ventura and later.

This is neither a macOS Ventura nor the OCLP thread. Please discuss all experiences on this thread: macOS 13 Ventura on Unsupported Macs

Known issues OCLP/Ventura:
  • 0.6.8+ is necessary for all iMacs beyond Ventura 13.2.1
  • Ventura 13.2.1 will still work with OCLP 0.6.1
  • Kepler patches are available. But perfect support is difficult to achieve and keep alive. Kepler uses the 3802 metal compiler, which has been ripped out of Ventura and later.
Notes:
  1. Do not update a @dosdude1 patched installation of Mojave or Catalina, please backup user data, make a clean installation, restore user data.
  2. Only AMD based systems with GCN4 cards offer 4K H.264 and 4K HEVC with OCLP.
  3. No AMD Navi support currently.
About Ventura support:
  • Disable automatic system software updates!
  • Disable automatic security updates (RSR). Those will break your installation.
  • An upgrade BT/WiFi to 4.0/802.11 a/b/g/n/ac would give you full support, the stock hardware needs patching and may even fail on Ventura updates, again!
  • There will be no longer delta OTA upgrades offered, on each minor macOS release upgrade you will get the full 12GB package to download. There is no way around this.
  • SideCar will not work, even with GCN4 GPUs and HEVC support.

This is neither a macOS Sonoma nor the OCLP thread. Please discuss all experiences on this thread: macOS 14 Sonoma on Unsupported Macs. Please do not use any beta versions of Sonoma. There is no support.

About Sonoma support:
  • Disable automatic system software updates!
  • Disable automatic security updates (RSR). Those will break your installation.
  • An upgrade BT/WiFi to 4.0/802.11 a/b/g/n/ac would give you far better software support (UC, AirDrop, etc.)
  • There will be no longer delta OTA upgrades offered, on each minor macOS release upgrade you will get the full 12GB package to download. There is no way around this.
  • SideCar will not work, even with GCN4 GPUs.
  • stock BT needs mostly a PRAM reset to work - especially when dual-booting with older macOS versions

To compare original and replacement cards running different macOS versions we created and populated three benchmark tables. Please check them out and add your own results after installing a new card.

OpenGL Performance

OpenGL performance can be measured using the free Unigine Valley on macOS. Use these standard settings as resolution of 1920x1080, quality Medium, stereo 3D disabled, Anti-aliasing Off to compare results. We are not interested in any Windows results because it uses a different OpenGL implementation. Please stay away from adding Windows results to the result sheets.

Notes:
Valley results depend on the CPU and gives better results on same systems/GPU setups when a faster CPU has been installed.
Results also depend on OS version and OpenGL implementation. We are not interested in any Windows results because it uses a different OpenGL implementation. Please stay away from adding Windows results to the result sheets. Since Apple is going to deprecate OpenGL no more development will take place and no performance optimization will happen. It is a dead end.

Metal Performance

The Metal framework has been introduced in 2012 needing new hardware (like HD4000 iGPU or NVIDIA Kepler dGPU).
Use GeekBench5 Metal or the more meaningful MetalBench software to measure the new GPU.

Note: GeekBench is hardly a valid benchmark. Results vary in a great way on the same system and macOS and depend on existing connected external displays. MetalBench runs only on Catalina and later.

Table of Benchmark Software and upload and result forms


Apple M1 (MacBookAir) Unigine Valley 57.5 FPS, 2405 Score

A: Not necessarily. This "fix" is more of a "mod" to revive our iMacs. Depending on your scenario, it will require a full iMac disassembly, knowledge of BIOS flashing, dremel tools for heatsink modification, careful handling of logic board components, system administration at a higher level and some Unix or terminal command line awareness. Please make a plan or read the plan provided here before jumping into this!
A: Your MXM card is likely running an incompatible BIOS and will need to be flashed with the correct one. This can be done from within Windows or Linux using NVFlash, or with a CH341a programmer. Some HP cards do not contain any BIOS and will not show up in the system until flashed (sometimes only possible with a CH341A clip!)
A: BIOS can be flashed in one of the following ways:
1. Use a hardware CH341a clip programmer with free flashrom software. You can use the flashrom software directly from the MacOS terminal following this installation guide. Only AMD cards and a few NVIDIA cards like the K610M, K1000M and K2100M cards can be used with the clip. Experienced users may solder a different BIOS chip onto those cards to be used with a clip, too. All other NVIDIA cards have so called WSON BIOS packages and need software flashing. One important note is many cheap CH341a clip programmer is setup to drive 5V flashroms. Some GPU card ROMs are 3.3V (need to find ROM on card and look up spec) so CH341a need to be modified (soldering) to program these flashroms ( example link ) Also some flashroms are not tall enough to for the typical cheap CH341a clip to grab on to the pins. For example, those on a WX4130.
2. Use a Linux USB pen drive with this latest version of the GMRL Linux flash tool. User guide included.
Thanks to @xanderon creating and @The_Croupier updating previous versions.
3. Use Windows 7: @jowaju created a simple Installer package that can be run on macOS Sierra (10.12) and higher that creates a 15GB Windows 7 Bootcamp partition with all the needed tools. You may need to update software tools.
4. Build a GRML from the distribution yourself? Check this post. Of course you need to add tools and vBIOS files manually, see below.
5. for experts: use amdvbflash.efi from the efi shell included with OpenCore (OCLP) - really nice summary post.
6. This post from @Nick [D]vB might be useful when setting the CH341A hardware up.
Notes:
AMD flash software and NVIDIA flash software is only available on Windows and Linux.
THIS external POST helps describes the flashing process. Others have found THIS POST useful.
Do a PRAM reset after flashing if you cannot boot into a known to work MacOS version!
A: No - all cards outlined in this guide use the included NVIDIA drivers in macOS. No additional GPU drivers are needed.
A: Recently iMac compatible vBIOS version for some Maxwell and Pascal cards have been published on this thread. macOS Mojave (10.14) deprecated support for the NVIDIA Web Drivers which allowed the use of Maxwell and Pascal cards. So these cards are perfectly fine for Windows and Linux. For now, Kepler GPUs and the (new) AMD cards seem to be our path forward when using Mojave or more recent macOS versions up to Monterey.
A: Yes! So far, the K1100M & GTX 770M have been tested firsthand and successfully provide 4K@60Hz output via mDP to DP adapter on a 4K display. Others should work just as well.
A: For the GPU any thermal Paste like Thermal Grizzly’s Kryonaut paste is good. For onboard components like VRAM, we strongly recommend using K5 Pro Viscous paste instead of thermal pads, due to the unevenness of the heatsink, it’s also similar to Apple’s original design. You can get it from the Bay or from the Book Store, too. How to apply the paste, watch this video!
A: You can get it from the Bay or from the Book Store, too. Literally everywhere you can buy a graphics card you will find the plates in different sizes and thickness.
A: A number of challenges and care must be taken regarding the X bracket. Read here.
A: We are still aggregating GPU benchmarks. There is a special section on this page and we added to the GPU tables a relative (to the old flagship HD6970) performance column only based on the the OpenGL benchmark.
A: For an MXM-A swap (the shorter/less power draw cards) there are no modifications that are needed for the heatsink on both the 21.5" and 27" model iMacs. The new X-clamp still needs be removed from the back of the card. Separate the X-Clamp using a hair dryer before drilling or tapping - it is just glued to the board. Skipping this step can fry or damage your card.
If you've cleaned your heatsink, be sure to re-apply thermal pads around the GPU VRAM to prevent contact with the bare metal of the heatsink. Use electrical tape to isolate card components from the sink! Watch closely after installing the card.
Take a look at the attached pictures of this post! In case you had a ATI card using a small Apple X-bracket (all MXM-A cards, 4850 and 5850) just reuse this bracket!! It fit's perfectly with all MXM-A , all NVIDIA and all AMD GCN replacement cards! The big Apple x-clamp can be used with the RX480, WX7100,W7170M, and S7100X.
In case you need to use the new x-clamp tap or drill out the rivets. Otherwise the screws will not fit.
A: The MXM-B cards only work on the 27" models due to power restrictions.
1. remove the glued x-clamp from the new card
2a. use a big Apple X-clamp with RX480, WX7100,W7170M, and S7100X (no grinding)
2b. use a small original Apple X-clamp with all other new Kepler or AMD cards (no grinding)
2c. tap out the rivets of the new x-clamp if your cannot follow step 2a or 2b
3. grind down your heatsink in the area where one or two large coils sit, this way the card will sit flush with the heatsink.
If you have a 2 pipe heatsink that came with the lower end GPUs on these iMacs and want to use an MXM-B Card, you'll have to buy a 3 pipe heatsink to cool cards properly.
Using a (battery powered) Dremel with tungsten carbide grinding cutters work fast and give you smooth result. Do not try other cutters!
A: Most likely the installation of card on the heat sink caused a short, or the card is simply faulty, or the card has not been reseated in the slot properly, check all this out first. Any hardware issue has to be solved by yourself!
A: We all know that none of the modifies BIOS versions for the Metal GPUs listed in the table above is able to provide the internal GPU temperature back correctly to by used by third party monitoring tools (Red Herring!). Nevertheless the iMacs internal Apple SMC software to control the (ODD) fan according to the GPU heat sink temperature still works perfectly, but it kicks in really late at 80C. To address this issue we recommended strongly to use a free software called Macs Fan Control. The optimal approach would be to solve this problem in general by using the ODD temp sensor.
A: The first term simply describes the fact that you can use GUI related operations like moving, resizing, closing an application or Finder window fast and smooth. This has been a serious issue with all patched installations of macOS versions on unsupported hardware. All "metal" cards listed above offer full graphics acceleration. Especially with Big Sur this has become more important since only "metal" enabled cards offer now the full graphics acceleration. The term video acceleration describes the hardware abilities of the GPU supported by the macOS. Only the new AMD GPUs offer 4K HEVC and 4K H.264 if installed in an iMac. If you want to know more about the possibilities AMD cards offer watch some of the videos collected here.
A: This issue has been described by the author of the BIOS on every publishing post. So it is a BIOS issue which can be solved by just sending your iMac once to sleep and on wake up the graphics driver will re-initialise and the color mapping will be correct or you simply use this little app made by @passatgt and follow his instructions.
A: Take a look at this post...this is not a plug and play task.
A: This feature is only officially supported until High Sierra on the iMac. Apple dropped TDM support for M1 systems using thunderbolt ports (iMac Mid 2011 and later). You can only use an iMac up to Mid 2010 as an external display for these new 2020+ machines. Check this thread for more details.
Manually triggering of TDM is now possible for 2009/2010 iMac in newer MacOS using a miniDP cable. Please see this post. Works with Thunderbolt 2 on iMac 2011 using Monterey and later, too - only sound transport is missing.
A: You will need a rainy Sunday to demount and clean your display, but it is worth the effort.
A: You will need a rainy Sunday to demount and repair your display, but it is worth the effort ( link1 link2 ) Link2 guide is done on a Thunderbolt Display which is same 27" LG display as 2009-2011 27" iMacs. Cabling to iMac and back of display cable probably slightly different. Internal panel and LED bar connector are identical.
A: Basically the panel seems to be the same, only the iMac facing part of the electronics changed over time. You can move this part from an 2009 panel to a 2011 panel and connect the 2011 panel to your 2009 iMac (or vice versa). Works with all models in all combinations. Take a look at this guide based on the discovery by @Airknight. You can even replace the panel within the complete display.
A: Try to add this PCB developed by @dfranetic into your iMac.
A: 1. This solution based on the ESP32 lost drivers support on Monterey. 2. You may follow this recipe. 3. More information about using a Pi, an app controlling the backlight via Pi.
A: Most sensors can have a simple replacement.
A: Just check this post.
A: First, read the recent part of thread and this post on a regular base. Staying on top of the progress here is key! And of course every user may help sharing his knowledge to new users - but please stay on topic!

Here a list of related external projects:
  • MXM carrier board with PCI extender to plug in an eGPU into 27 Late 2009-2011 iMacs from iBoff
  • Kryptonite eGPU revival (possibly without TB1/TB2 support, though)
  • dosdude1 working on iMac12,2 CoreBoot project to enable IvyBridge support
Here some realized projects worth being mentioned on this post:
  • Injection of a vBIOS in case modding does not work or no BIOS chip is on board.
This is a short list of enhancements worth to be realised IMHO:
  • work on iMac 2011 Thunderbolt Target Display Mode with Big Sur or Monterey, the Late 2009/Mid 2010 DisplayPort version has been explored already with success after years of pain. Works on Monterey and Ventura, but nobody has noticed it?
  • modify iMac Late 2009 i-series firmware to avoid total eclipse (black screen) (solved with OpenCore with agdpmod=vit9696 and since we use OpenCore for all Mojave+ installations it could be considered as solved!)
For those about to solder or code, we salute you!

Here the most frustrating (vBIOS or hardware or software) problems:
  • why do VER 1.0 AMD MXM cards still not POST in the iMac12,2 2011 system ( RX480, WX7100) (more likely card hardware issue)
  • AMD GCN GPU break wake after sleep on iMac12,x systems. Recent tests with iMac12,2 gave the following results: Crash on wake in normal mode. Can be a simple race condition since a few systems seem unaffected. BIOS mods (like disabling the iGPU) did not fix it.
  • some AMD GCN GPU have problems to sync with external displays on boot (need display sleep to sync, this is clearly a GOP+iMac firmware problem). It goes away with all EG2 vBIOS versions (no GOP) and comes back when AMDGOP driver has been re-loaded by OpenCore.

Most - if not all - of these problems have been solved with the published BIOS versions. So this is more a history lesson or a Tour d'Horizon. Using a non Apple PC MXM video card within an iMac will create these seven problems mention below, i.e. you will loose EFI boot scree, backlight control, Target Display mode, etc.

All NVIDIA cards listed support EFI boot screen (pressing alt/option on boot). All AMD cards using a GOP vBIOS support the OpenCore boot screen (pressing ESC on boot). All AMD cards using an EG2 vBIOS and firmware mod or using EG vBIOS support EFI boot screen, too.
There is a small delay between the chime (POST) and the initialisation of the actual boot screen on all replacement cards.
Most of the time (such as a warm reboot in macOS) the system boots too quickly for the EFI portion of the BIOS to initialize, making it appear that you may not have a "boot screen." All is working as intended if you can hold the alt/option key at startup and get a boot picker.

Brightness control is available for all cards listed. Some may need OpenCore to enable it. Some Nvidia cards need another fix to reach maximum brightness. This patch is included in OLCP and is based on work by @highvoltage12v.

For other cards, brightness control may be added in the future. Be aware that without any brightness control, the iMac display runs at full brightness by default. On 27" models this will generate a lot of heat.

Software Solutions:
1. iMac PWM Control, which works better than most apps in the App Store, because it will dim the colors on the whole screen and it will display the built-in OSD, just like native brightness control.
2. MonitorControl, a free solution for all displays connected to you Mac lacking hardware brightness control
3. Brightness Slider, which is available on the App Store for free.

Hardware Solutions:
1. Raspberry Pi and iMac PWM Control by @passatgt
2. TL494 PWM module by @wlagarde
3. ESP32 by @Lottosmp (CP2102N driver support unclear with Monterey)

Despite having two thunderbolt 2 outputs (supporting mini display port connected displays) , the 27" 2011 iMac12,2 will only output to one external display using the port close to the FW port. There is currently no fix or general workaround for this. Some cards (like the WX4130/40/70) allow to drive a second display through a TB2 dock! Only the RX5500XT enables both ports.

Basically target disk mode (pressing T on boot) is now supported with cards offering an EFI boot picker.

Target Display Mode (TDM) is available on cards offering an EFI boot picker. So basically new NVIDIA cards or AMD cards with EG2 or EG vBIOS can provide TDM functionality on High Sierra, again.
Check this Q16 from FAQ about limitations. Check Apple support pages to understand needed cables and limitations of supported connections.
Monterey brought back TDM, but it is not 100% stable und sometimes disconnecting needs a reboot of the iMac.

AHT was broken with GOP vBIOS. Use the new EnableGop (EG) or EG2 vBIOS versions to run the internal service diagnostics. You may search the net for the ASD (Apple Service Diagnostic) package instead. For each system there is a different package. Download and install the package onto a SD card or a DVD, which will give you full functionality. A working download link may be difficult to find. It is not open source. Another download site

No replacement card reports the GPU temp correctly to Apple macOS software tools. But this does not break controlling the ODD fans, the ODD fan control is dysfunctional by Apple design. Apple and all customers wanted a silent machine on the desktop and customers got fried graphics cards in return. The Apple internal SMC (System Management Controller) still controls the ODD fan. Observations showed the fans ramp up starting and 80C and higher on the heat sink, but this is (IMHO) a death sentence for electronics. You should either use the free Macs Fan Control software or better relocate the ODD temp sensor. This sensor will drive the ODD fan up using the Apple SMC software starting at 55C. It works in any case, even when using Linux or other OS versions or during longer macOS installation processes. Even AMD offers a Zero RPM solutions for new PCI cards stopping the fans below 60C - so we are perfectly save with our 55C choice here.

macOS GPU temp monitoring is still possible using third party tools, these can report a GPU temperature. But it has only dashboard functionality, viewing this temp does not change the fan control by the SMC.

If you look closely into the GPU tables you will find a row named Heat Sink which indicates both the compatibility with your system (21,5 or 27) and if there is a physical modification using a Dremel needed. Since most people miss this crucial information I decided to collect it and put it here together again:

Heat Sink TypeThermal Design Power (TDP)iMac Models (source)
MXM-A35Wused in all supported iMac models
MXM-B until mid 201050W27 iMac10,1+iMac11,1+iMac11,3
MXM-B mid 201175Wonly 27 iMac12,2

The MXM3 slot can handle enough current to provide 75W sustained in 27" models. So you can mix and match heat sink and cards between those bigger iMacs.

Solving this riddle from the other side one can list cards in the same TDP range:

Thermal Design Power (TDP)Card Name
<= 35WK1000M, K1100M, K2000M, AMD M4000, K2100M, AMD M5100, AMD W5170M
35W < TPD < 50WAMD WX4130, AMD WX4150, AMD WX4170, AMD WX3200, AMD M6000
= 75Wall other MXM-B cards listed here in the GPU tables


All MXM-A cards will run on MXM-A heat sinks but you will observe higher fan speed needed compared with using the very same card type on a bigger MXM-B heat sink. The bigger the sink the more effective it will dissipate the heat. If you have a bigger sink please use it!

Please note the AMD M6000 and AMD WX4170 are full sized MXM-B cards and will not fit properly into 21.5 iMac models. @internetzel reduced the TPD of the RX480 to 67W just because users experienced shut downs in long gaming sessions. The fans cannot remove the heat from the iMac through the small holes in the top and bottom.

One can - of course - drill bigger holes into the bottom (air input) and top (heat exhaust) to avoid this.

BTW:
Do not place the iMac in front of a south directed windows - the heat of the summer and the sun will do the job even with low load on the card. People living in non moderate climate zones will know what I mean.

Please do not harass the BIOS developers to go faster, release a particular BIOS, etc. Please do not clog up the thread with useless posts asking if your specific card will get a new BIOS. Usually it takes several months of reverse engineering and testing before getting a new BIOS working.

~~~~~~~~~~

Original Post from @MichaelDT June 14th, 2013.

I will be attempting to upgrade the MXM card in my 2011 21.5 iMac from the factory 6770m 512mb to a NVidia 675m 2GB. I choose this card because the chipset already has support from 10.8.3 onwards and affordability for an experiment. I am hoping that it will work without flashing like many of the other non MXM modern graphics cards (UEFI support) do in 64bit EFI Mac Pros ( I may loose the initial boot screen). But if all else fails I will attempt a flash. I will report back my findings when the card arrives (from Hong Kong). Wish me luck hopefully this will give those of us with the last modular iMac a path forward.
 

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SpeedFleX

macrumors 6502
Apr 22, 2009
301
2
Interwebz
I will be attempting to upgrade the MXM card in my 2011 21.5 iMac from the factory 6770m 512mb to a NVidia 675m 2GB. I choose this card because the chipset already has support from 10.8.3 onwards and affordability for an experiment. I am hoping that it will work without flashing like many of the other non MXM modern graphics cards (UEFI support) do in 64bit EFI Mac Pros ( I may loose the initial boot screen). But if all else fails I will attempt a flash. I will report back my findings when the card arrives (from Hong Kong). Wish me luck hopefully this will give those of us with the last modular iMac a path forward.

Good luck brave sir!
 
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cmanderson

macrumors regular
May 20, 2013
161
0
I will be attempting to upgrade the MXM card in my 2011 21.5 iMac from the factory 6770m 512mb to a NVidia 675m 2GB. I choose this card because the chipset already has support from 10.8.3 onwards and affordability for an experiment. I am hoping that it will work without flashing like many of the other non MXM modern graphics cards (UEFI support) do in 64bit EFI Mac Pros ( I may loose the initial boot screen). But if all else fails I will attempt a flash. I will report back my findings when the card arrives (from Hong Kong). Wish me luck hopefully this will give those of us with the last modular iMac a path forward.

Let us know how it goes, and if it works for you, what sacrifices you've had to make, if any. Also, links or contact info to your resource in HK.
 

MichaelDT

macrumors regular
Original poster
Aug 18, 2012
204
235
Excellent news it is exactly as I suspected, you simply need an mxm a/b card that supports UEFI. I did loose my initial boot screen but once OSX loads the screen powers up. So initially I ordered the 675m but when I received that card it had BIOS only drivers...so I ordered a DELL/Alienware 680M off ebay. Only Trouble so far is it isn't recognizing my second display, but I'll tinker and we shall see if I can fix that.:)

Edit: So looking at my console logs it senses the second display then drops it, I'm thinking it is the driver.
 

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MichaelDT

macrumors regular
Original poster
Aug 18, 2012
204
235
More details: If you use an MXM-B card it will be larger than the MXM-A card that the ATI is; so it will hang over the HDD. It doesn't cause any issues though, no modifications needed. During the install the heatsink from the ATI 6770M is a just a tiny bit too small, half of one of the ram chips will be uncovered. This doesn't seem to be a big deal as it is the chip positioned closest to HDD fan and I have been monitoring the heat sensors and they don't seem an higher that with the ATI card even playing graphics intensive games.
 

QCassidy352

macrumors G5
Mar 20, 2003
12,034
6,068
Bay Area
Well done sir!! Very nice. Wish I had the guts to do this to my 2011 21.5". You'll have to give us some performance numbers when you get a chance to play around with it. :)
 

kgian

macrumors regular
Jul 17, 2011
187
8
Congratulations!
How can you boot to windows bootcamp if you lost the bootscreen?

Also, can you post a link to the mxm board you baught?
 

MichaelDT

macrumors regular
Original poster
Aug 18, 2012
204
235
Concerning bootcamp etc see this thread The concept is just the same, only instead of standard PCI iMacs use NVidias MXM 3.0 protocol which really is just PCIe anyways.
 

goodcore

macrumors newbie
Jun 24, 2013
16
3
Putinville
Hello MichaelDT!
Thank's for your research
I also trought with replacing graphic card in my iMac 27 over my factory 6970M. But i want install 7970M. Keep in touch.

Vasily
 
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StevieRay

macrumors newbie
Jun 24, 2013
7
3
This may be a dumb question, but can you swap the video card on a 15" MBP (non retina) like this, or is it soldered to the MB?
 

mikeylam

macrumors newbie
Jul 12, 2013
7
0
Hi Michael, I am a bit confused by the below. What do you mean by "So initially I ordered the 675m but when I received that card it had BIOS only drivers...so I ordered a DELL/Alienware 680M off ebay."?? I would think if you install the 675M into the system, OSX should just load the driver automatically? Why would the card come with OSX drivers as they are PC cards anyway?

Excellent news it is exactly as I suspected, you simply need an mxm a/b card that supports UEFI. I did loose my initial boot screen but once OSX loads the screen powers up. So initially I ordered the 675m but when I received that card it had BIOS only drivers...so I ordered a DELL/Alienware 680M off ebay. Only Trouble so far is it isn't recognizing my second display, but I'll tinker and we shall see if I can fix that.:)

Edit: So looking at my console logs it senses the second display then drops it, I'm thinking it is the driver.
 

Commy1

macrumors 6502a
Feb 25, 2013
730
76
Canada
That's an impressive upgrade, I'm impressed. Are there any heat issue? or even noticeable higher temps? The 680 is a beast card, I wouldn't be comfortable putting it inside such a confined space, but if it works, why the heck not.
 

omvs

macrumors 6502
May 15, 2011
495
20
Is there any way to get the boot-screen? I was excited and ordered a 680M, though now I'm wondering if this means I won't be able to boot with File Vault enabled....

I did see some posts about updating the firmware to get EFI for win8, but it sounds like your card has the EFI firmware update and still gives no boot screen?
 
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pastrychef

macrumors 601
Sep 15, 2006
4,753
1,450
New York City, NY
Nice job! It may be possible to get back boot screen image if someone with an iMac that came with a GTX 675MX gives you an image of the ROM.

You mentioned that the stock heatsink is too small and leaves some of the VRAM exposed. I don't know if theres, enough room, but you can try some of these:
 

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jezzy

Suspended
Jan 12, 2012
85
1
Montreal, Quebec
Very brave. Thanks for sharing! I'm personally looking at upgrading my iMac mid 2010 27" 5750 1gb to a 2011 6750 card.. But can't swallow a 600$ price tag!
 
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