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macrumors regular
Original poster
Aug 18, 2012
iMac Late 2009 to Mid 2011 graphics card upgrade
(Lastest update 02/21/2022)

This is not 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 and make notes while reading through this page several times and check the thread!

It is HIGHLY recommended that you read through this post before asking questions. Then, reread the 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.

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. It takes several months of reverse engineering and testing before getting a new BIOS working.

There is no simple best card: Your budget, your comfort level with doing modifications, your ability to live with unresolved issues, your computing needs, the local market, your iMac model, etc. will determine the card to be used.

Unfortunately, this thread cannot help you source cards as there are too many variables involved.

Read through this information carefully in order to choose the best card for your needs.
  1. The modified (NVIDIA video) BIOS with EFI boot screen version require an Intel i3 CPU or better (see also below #5). Same applies to AMD EG BIOS versions offering EFI boot screen, these machines are: iMac11,x and iMac12,x systems.
  2. The AMD GOP vBIOS version using OpenCore to provide a boot screen work perfectly also with the Late 2009 27 iMac10,1. Check also #6
  3. In general only Nvidia Kepler, or AMD Baffin, Ellesmere, Polaris20, Polaris21, and AMD GCN cards will work in these iMacs with macOS including Monterey. No other (Nvidia) GPU variant has macOS driver support.
  4. There are smaller MXM-A cards and bigger MXM-B cards running stable only in the 27" models. While all cards may function in a 21.5" model, the big ones are unstable due to their high power draw. Do not try it!
  5. Most NVIDIA MXM B and most AMD 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. Check the tables for details.
  6. Core2Duo CPU systems: Tests with iMac10,1 21.5" Late 2009 and iMac9,1 24" Mid 2009 and the Late 2009 27 iMac10,1 with a new GPU have been made. External displays worked in any case, internal LCD within the 27 Late 2009, the others needed you to buy a special driver board and connect the internal screen with the external miniDP port (and make it an external one). One user reported the internal LCD would work after letting the system sleep. Check carefully which driver board you might need. Some other cards may work with the stock BIOS showing all the seven problems... work is ongoing. This is a vBIOS problem. Another user installed a Nvidia GT120 successfully in his 27" iMac10,1 using the Apple BIOS made for the former A1224/A1225 models. This card is Tesla based and offers no metal support.
  7. The fan control is broken after replacing the GPU. While we can monitor the GPU temps using different software solutions the Apple internal SMC (System Management Controller) refuses to control the ODD fan according to the heat generation on the GPU and heatsink. You need to use either the Macs Fan Control software or replace the ODD temp sensor. See below in the The Seven Problems section and read the #7 description.

Most - if not all - of these problems have been solved with the published BIOS versions.

Using a non Apple video card within an iMac will create these seven problems.
  1. The loss of EFI boot screen;
  2. The loss of backlight control;
  3. You can only connect one external monitor to 27" iMacs;
  4. The loss of Target Disk Mode;
  5. The loss of Target Display Mode (TDM); (works only with High Sierra and before)
  6. The loss of running the built-in Apple Hardware Test (AHT);
  7. The loss of temperature sensors on the new GPU. But there is a hardware solution!
1. Boot Screens are now available on all listed cards using custom VBIOS and/or OpenCore

You may use the OpenCore booter to add a boot screen feature to every card - even the Nvidia and AMD cards not listed here or known to have no BIOS support to show the original apple boot picker.
There is a small delay between the chime (POST) and the initialisation of the actual boot screen on the current NVIDIA modded BIOS. 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 "Option" key at startup and get a boot picker.

2. Native Brightness control is available for cards marked with + or ++ using a combination of custom BIOS and OpenCore.

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

If you would like to "dim" your display using color dimming, many have used the app Brightness Slider, which is available on the App Store for free.

You can also use this app, 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.

Additionally, hardware level modifications using a DyingLight module or a Raspberry Pi have been used for brightness control. This software written by @passatgt can be run on a Pi for backlight control. Another hardware solution can be found here.

Nvidia cards marked with ++ with native brightness control may notice their displays are not hitting maximum brightness control Potential. A kext modified by @highvoltage12v can be found here to fix this issue. It has been added to all installer packages and the Bit Sur patcher.

Last, but not least: User @Lottosmp came up with a solution based on the former engineering.

3. Despite having 2 miniDisplayPort outputs, the 27" 2011 iMac will only output to one external display. There is currently no fix or workaround for this.

4. Target Disk Mode is available on all cards marked with a + or ++!

5. Target Display Mode (TDM) is available on for cards marked with + when using both custom BIOS and OpenCore. Check this Q16 from FAQ about limitations.

6. Apple Hardware Test (AHT): There is currently no fix for running 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 hard to find. It is not open source.

7. GPU Temperature Monitoring is available on most new card when using both custom VBIOS and OpenCore. This shows the temps, but does not control the fans!
Use Macs Fan Control to control the ODD fan. Check the PDF attached to this post for details. The best solution as of today is to relocate the ODD sensor as described in this solution! The ODD sensor will drive the fan up using the Apple SMC software.

Please read the issues section first! Most of these cards hit the street before 2012 and are considered as old cards.

  1. Old cards: A lot of the a 7-10 year old used Nvidia on the market 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!
  2. iMac 2011: Some NVIDIA GPU may not run well 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. Sometimes the same error is related to connecting and disconnecting the single internal SSD. Meanwhile we believe the root cause are address conflicts on the SMBUS caused either by the GPU or some IC on the card connected to the SMBUS delivering thermal date. Sometimes you can visualize such problems with tools like HW Monitor. If you find additional weird temperature readings you might have such a card. No software solution possible! Lately on user made this modification and got his K3100M working.
  3. sleep/wake broken: In some 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!
  4. 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.
  5. Black Screen: After complete installation of the iMac the internal LCD can stay black, only three status LED light up. This is the black screen software issue. Normally you can get around it (temporarily) by pressing alt/option on boot. Late 2009 system you will face (only there) a more severe variant. After a PRAM reset the LCD gets and remains black. To fix this for all iMacs a kernel extension needs to be patched at best in advance. Only after booting into this patched macOS the internal LCD will come back. 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. Alternatively OpenCore (e.g. OCLP) with agdpmod=vit9696 in the boot-args fires up the LCD after a PRAM reset or GPU change, too.
  6. Color depth problem: Happens on after boot - just sent the system once to sleep or change resolution. This solution or this opencore based solution may cure the problem.
  7. Brighness level: Solution is linked here for all ++ cards and described by @nikey22 on each of his posts, again.
  8. Brightness control with OpenCore: All + cards need OCLP or CL to enable brightness control and this solves the black screen issue using the agdpmod=vit9696 in the boot-args at the same time.

CardBIOSBIOSBoot ScreenBrightness Control21.5/27/MXMHeat Sink ModOGLMET
Quadro K500Mnonoyes/yes/An/an/a
Quadro K510Mnonoyes/yes/An/an/a
Quadro K610M +ROMyes (OC)yes (issue 7 above)yes/yes/Aspecial install505n/a
Quadro K1100M +ROMElpidayes (OC)yes (issue 7 above)yes/yes/Ano907n/a
Quadro K2100M +ROMElpidayes (OC)yes (issue 7 above)yes/yes/Ano1229n/a
Quadro K1000M +ROMnoBCyes (OC)yes (issue 7 above)yes/yes/Ano903n/a
Quadro K2000M +ROMnoBCyes (OC)yes (issue 6 above)yes/yes/Ano797n/a
Quadro K3000M ++ROMROM1yes (natively)yes (issue 6 above)no/yes/Byes, 3 pipe116415
Quadro K4000M ++ROMyes (natively)yes (issue 6 above)no/yes/Byes, 3 pipe1680n/a
Quadro K3100M ++ROMROM1
yes (natively)yes (issue 6 above)no/yes/Byes, 3 pipe177921
Quadro K4100M ++ROMyes (natively)yes (issue 6 above)no/yes/Byes, 3 pipe246532
Quadro K5000M ++ROMROM1yes (natively)yes (issue 6 above)no/yes/Byes, 3 pipe203829
Quadro K5100M ++ROMyes (natively)yes (issue 6 above)no/yes/Byes, 3 pipe2404n/a
GTX 680M ++ROMyes (natively)yes (issue 6 above)no/yes/Byes, 3 pipen/an/a
GTX 765M +ROMyes (OC)yes (issue 7 above)no/yes/Byes, 3 pipe1428n/a
GTX 770M +ROMyes (OC)yes (issue 7 above)no/yes/Byes, 3 pipe2140n/a
GTX 780M +ROMyes (OC)yes (issue 7 above)no/yes/Byes, 3 pipe264241
GTX 780M ++ROMyes (natively)yes (issue 7 above)no/yes/Byes, 3 pipe264241
GTX 880M ++ROMyes (natively)yes (issue 7 above)no/yes/Byes, 3 pipe2700n/a
GTX 860M ++ROMyes (natively)yes (issue 7 above)no/yes/Byes, 3 pipe161634
GTX 870M ++ROMyes (natively)yes (issue 7 above)no/yes/Byes, 3 pipe232640

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.
OC: OpenCore

BIOS by @Nick [D]vB that currently enable boot screens on your iMac.

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.

  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 would make OpenCore for any listed card necessary!
  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!
  5. Latest working macOS is Monterey Beta 6. Beta 7 discontinued Nvidia Kepler support but OCLP starting with version 0.2.5 is able to patch support back. This patching does not bring 100% functionality back, e.g. OpenCL support in Photoshop is missing on Monterey

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 offspring thread.

You will find special vBIOS versions searching this not so long thread.

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.

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 and RX480 and RX470 (mobile)
    Currently we assume that only 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 post and run in an iMac12,2 (Mid 2011) while the version 1.0 will only run in Late 2009 and Mid 2010. RX470/RX480 cards are version 1.0 only - and do not work in Mid 2011 iMac systems!
  2. 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)!
  3. 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 iMac12,2 21.5 inch models. Check your card before applying any mod.
  4. problems with cards: Unlike the NVIDIA family where we get each week several reports of dead cards we had so far only two reports showing a not properly working Dell WX4150 and a HP WX4170 - the problem have been solved by adding more VRAM support. Unfortunately we now have to chose from several published versions.
  5. Initial setup: Using High Sierra the GOP vBIOS disables the internal LCD on power on.
    Work around: Use an additional external display on boot.
    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).

CardBIOSBIOSBoot ScreenBrightness Control21.5/27/MXMHeat Sink ModOGLMET
AMD WX3200
ROM1yes (OpenCore)yes (natively)yes/tbd/Anotbdtbd
AMD WX4130 +++oldROM1yes (OpenCore)yes (natively)yes/yes/Aspecial install180553
AMD WX4150 +++oldROM1yes (OpenCore)yes (natively)yes/yes/Aspecial install180562
AMD WX4170 +++oldROM1yes (OpenCore)yes (natively)no/yes/Bspecial install215673
AMD RX480 +++oldROM1yes (OpenCore)yes (natively)no/yes/Byes or no?, 3 pipe2800150
AMD WX7100 +++ROMROM1yes (OpenCore)yes (natively)no/yes/Byes or no?, 3 pipe2949170

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 Beta 10.

GOP and OpenCore boot screen:

Using the GOP 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).

EFI boot screen:

Using the EG BIOS version you will get a native Apple boot picker with an iMac firmware modification on an additional external display, only. These BIOS versions offer native brightness control, too. You can also use the same OpenCore setup as with the GOP BIOS versions to enable 4K H.264/HEVC. Here you will find new EG BIOS versions for the WX4xxx line. Both solutions have their own advantages.

Adding a hot wire mod described in detail in the great post you can get the EFI boot screen visible on the internal LCD, too.

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

This table shows cards with experimental support. Cards have been published between 2012 (M4000) and 2015 (W7170M).

- 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.
- 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
- all cards support AirPlay with Catalina on all iMac11,x and iMac12,2 using OCLP (Lilu/WhateverGreen)
- all cards seem to support AirPlay to Mac with Monterey
- 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, use the M5100 (hardware issue, needs modding the card)
- 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
- if you find two ROM links we have later added new VRAM support, please check your card visually and the posts containing the different vBIOS versions.

CardBIOSBoot ScreenBrightness Control21.5/27/MXMHeat Sink ModOGLMET
AMD M4000ROMyes (OpenCore)yes (natively)yes/yes/Aspecial install80919
AMD M6000ROMyes (OpenCore)yes (natively)no/yes/B2 pipe MXM-B101030
AMD M5100ROMyes (OpenCore)yes (natively)yes/yes/Aspecial install98331
AMD W5170MROMyes (OpenCore)yes (natively)yes/yes/Aspecial install77831
AMD M6100ROMROM2yes (OpenCore)yes (natively)no/yes/B2 pipe MXM-B102430
AMD W6170MROMyes (OpenCore)yes (natively)no/yes/B3 pipe special install180557
AMD E8870no/yes/B3 pipe special install
AMD W7170MROMyes (OpenCore)yes (natively)no/yes/B3 pipe
AMD S7100XROMyes (OpenCore)no (hw mod needed)no/yes/B3 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.

These AMD cards have been published between 2012 and 2016 and use macOS HD7000 and HD8000 driver stack. The cards are supported natively with 10.8.3 and later. Latest known working macOS version is currently Monterey.

The E8870 seems to be a 4GB version of the 2GB W6170M. So in case someone comes up with a vBIOS from the card the modification will be fast to realize.

This is highly experimental and I do not know if another user is willing to sacrifice a perfectly working Sonnet eGPU, but here you find preliminary results with an RX 5500 XT AMD Navi GPU in an iMac11,3. This GPU has been released in 2019.

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, 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 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 three 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.
2. Use a Linux USB pen drive. @xanderon created and @The_Croupier updated a pre-configured Linux USB image that can flash all Nvidia and all AMD cards in the iMac with Linux over SSH. Many have found this the easiest method. It needs a direct wired Ethernet connection between iMac and Router and can be used remotely from an SSH client when the iMac display is still dead. SSH clients are available for iPad, iPhone and other tablet devices, too. If you cannot connect to your iMac using the ssh command because of this message WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! delete the known_hosts file entering this terminal command: rm ~/.ssh/known_hosts.
If your router does not provide an IP automatically to new devices on the local network check and change its config.
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.
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: 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. There is one additional mod needed to make the MXM-B card fit. First you must grind down your heatsink in the area where one or two large coils sit, this way the card will sit flush with the heatsink. You must prepare the the X-clamp in the same way as described with MXM-A cards above. 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 replacement cards except the RX480, WX7100,W7170M, and S7100X!
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.
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 the iMacs internal Apple SMC software to control the (ODD) fan according to the GPU internal temperature. To address this issue we recommended strongly to use a free software called Macs Fan Control. But you can also try to solve this problem 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.
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.
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!


Do not use
the @dosdude1 patcher with any iMac10,x or iMac11,x model!
OCLP is by far superior and one and only supported solution on this thread, no exception!

What is OpenCore?

OpenCore (OC) is software to enable some features and to provide necessary data before an unsupported or supported macOS boots. This way we can solve sleep/wake and black screen issues without modifying (aka patching) the original Apple macOS installation itself.

The most easy way to use OpenCore is by using the OCLP tool. Please just follow the online docs provided.

The Highlander rule applies here (There can be only one OpenCore installation in a single EFI partition on your iMac). Having installed OpenCore to several EFI partitions can break your installation seriously and with weird side effects. So take a note where you put this software and keep track of if!

AMD GPU users with a GOP vBIOS have no EFI Boot screen! So they cannot control the boot selection on boot! OpenCore offers a boot picker for those cases, but to use it OpenCore needs to be booted per default on power on. This setting is stored in the PRAM. So resetting the PRAM or changing the OpenCore config manually may delete this setting and you loose your boot picker which may leave your system unbootable.

How to keep the OpenCore boot screen alive?

Lately we discovered how to create a OpenCore Recovery CD. You can create one in advance or using OLCP on a different machine even after loosing a working internal OpenCore installation. After a PRAM reset you can force booting the CD pressing the C button on power on. The only other method is maintaining a High Sierra partition which will be booted after PRAM reset automatically. But this causes problems with Big Sur and Monterey APFS partitions.

Owners of NVIDIA cards with an EFI Boot screen can install the EFI folder directly to the EFI partition of the internal disk (process described in the OCLP docs). Having an EFI Boot screen one can always boot without OpenCore just by pressing alt/option on boot and selecting a supported macOS version like High Sierra.

Why using OC or OCLP!
  1. Native and unpatched installation of Mojave, Catalina and Big Sur with OpenCore Legacy Patcher (OCLP)
  2. Brightness control with K610M, K1100M, K2100M, GTX765M, GTX770M, (GTX780M) cards
  3. Emulated boot picker for all systems using AMD cards or NVIDIA cards having no EFI vBIOS!
  4. WINDOWS 10 UEFI installations on Mid 2011 sound patch
  5. AMD Video acceleration 4K HEVC and 4K H.264
  6. OTA (over the air) Apple software upgrade on Monterey, Big Sur, Catalina, and Mojave.
  7. AMD DRM (HW support) for Netflix (not in Safari), AppleTV, Amazon Prime etc. streaming
  8. solves black screen issue with all NVIDIA GPU (using agdpmod=vit9696 in boot-args)
Where to get it and how to use?

Download: OpenCore Legacy Patcher
Please do not change any of default values (like SIP) neither using the GUI or TUI version. You will only break the installation.

More in-depth information:

Thread: macOS 11 Big Sur on Unsupported Macs
Thread: macOS 12 Monterey on Unsupported Macs
Thread: OpenCore on Legacy Apple Hardware (focusing on MacPro, but also a lot of general instructions)
Thread: Activate AMD hardware acceleration

Videos: How to maintain OpenCore
Full OpenCore Legacy Patcher documentation
Full OpenCore documentation


Catalina Loader (CL) is another software allowing OC to be installed and maintained more easily than on hidden EFI partitions

Download (for Sierra and High Sierra): 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

OpenCore can only boot UEFI installations. Legacy installations will not show up in the OC boot picker. Because we need OpenCore for most graphics cards UEFI installation is the best choice.
Follow this link to install Windows using the UEFI method or search the net for more ways to achieve this. You will need OpenCore to enable the sound on 2011 systems using this method! To avoid blue screen issues on the iMac12,x read this doc. In case you lost your Windows EFI boot entry accidentally after installing OCLP take a look at this post how to recover it.

Mid 2010 and Mid 2011 can have two SATA drives installed. Doing this will stop the UEFI Windows installer from copying the installation files from USB install media to the target disk. The only solution I found was disconnecting temporarily the second internal disk until the installation has been finished.

Users of UEFI Windows installation should check the contents of the internal EFI folder. You can both install OC and MICROSOFT sub folder in EFI. Using OCLP TUI choose 14. Advanced Patch Settings, for developers only, then 4. Set Generic Bootstrap and finally 2. EFI/BOOT/BOOTx64.efi. Then go back to the main menu and 1. Build OpenCore and 2. Install OpenCore to USB/internal drive.

According to this list the (Kepler) Nvidia drivers are part of macOS since 10.8.3. You might check this out on your own. At least on recent successful upgrade of an iMac 12,2 with macOS 10.10 can be reported here.
According to this GPU buyers guide the new AMD will be supported with macOS Sierra and later.

Supported MacOS version can be installed using the original Apple installer. To avoid the black screen issue install this package.

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!

The recommended method for AMD GPU users is to have an OpenCore recovery CD prepared. This way you can force boot the CD pressing the C key on boot and get the OpenCore boot picker working in any case.

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 macOS 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. This is the future proof solution. First read the documentation linked on the download page.

The OCLP patcher TUI 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.

If you plan to use/install High Sierra or Mojave or Catalina using OCLP follow the manual approach described below.

If you plan to use/install 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 currently unsupported by the OCLP dev team but it works like a charm. You can set everything according to your needs and even generate configs for different systems by bypassing the auto detection. Start with changing the model.

After Mojave/High Sierra installation you can fix the PreBoot/Recovery of both these macOS versions and reset SBM and SIP to true. This way you can use OCLP to boot into High Sierra, too. It enables the superior 4K HEVC and 4K H.264 as it contains the brightness control patches. No need to fix a Catalina installation!

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

Known Issues 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!!)
  • 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.
Known Issues with Big Sur 11.6+:
  • 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 AMD41x0 on Big Sur breaks screen recording (use a third party app). This happens even with supported systems. Fix is using this command defaults write CMIO_Unit_Input_ASC.DoNotUseOpenCL -bool true
  • Airplay to AppleTV is broken (needs BT/WiFi update, regardless which other hardware the best you can get is sound output, screen remains black)
  • Using new AirPods and HomePods needs BT/WiFi update
Known Issues with Monterey 12.3+:
  • Kepler support has been dropped
    solution: patching back Kepler support has been introduced with OCLP 0.2.5 using post install patching
  • 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
  • on Monterey even supported BT and WiFi devices work unstable
  • UC works on iMac12,x only and needs BT/WiFi upgrade and AMD GCN 4 dGPU
  • AirPlay to Mac needs BT/WiFi update and works on iMac12,x with AMD GCN 4 dGPU, only (AFIAK)
  • Using new AirPods and HomePods needs BT/WiFi update
  • 12.4 needs OCLP 0.4.6 (development build) to support original BT hardware
Known issues OCLP:
  • use the GUI only with OCLP 0.4.0 and later, otherwise use the TUI
  1. Do not update a @dosdude1 patched installation of Mojave or Catalina, please backup user data, make a clean installation, restore user data.
  2. The stock Atheros WiFi and old BT works with both options, too. No HandOff and no Continuity, of course.
  3. AMD based systems offer 4K H.264 and 4K HEVC with Big Sur, again. DRM is working again and so Apple TV will show movies online, Netflix (currently not in Safari), Amazon Prime and others should work, too.
  4. Nvidia based systems cannot get iGPU based H.264 QuickSync acceleration back on Big Sur and later! So no Airplay using NVIDIA dGPU on iMac12,x systems.
  5. OCLP can be used without any patching and if offers SIP, File Vault and most importantly OTA upgrades. No other tool can offer this!
  6. AirPlay will work with every listed AMD dGPU and Mojave and Catalina using the original Atheros WiFI card. Big Sur needs a BT/WiFi and AMD GCN 4.0 dGPU upgrade, but AirPlay remains broken. No tests made with NVIDIA dGPU.

This is a legacy patching instruction. We strongly recommend to use OCLP to install any macOS Mojave and 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!

The recommended method is to have High Sierra as your primary OS and install Mojave/Catalina alongside on a separate partitions or APFS container partition. So if anything goes wrong, you can still boot back into High Sierra to fix issues. High Sierra offers a working recovery partition, too.

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: 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. You will avoid this patch (since you will use a new, compatible metal graphics card) and will need to modify a plist file if you are using a 2009/2010 iMac with a Metal compatible video card or more easily while building the patcher, you can go to the "Options" menu and de-select "Auto-Apply Post-Install Patches" to avoid this.

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).

1a. The process for Catalina is similar to Mojave as mentioned above. Use dosdude1's Catalina patcher to do the installation.

1b. Getting the latest Catalina installer is broken with the latest @dosdude1 patcher. You need the gibMacOS utility to download the latest version and construct it from the several download files. Follow the instructions coming with the tool. Then in can be installed using the latest @dosdude1 patcher. This method works for all recent macOS versions!

2. GPU and machine related patches:
Mid 2011: Install this package to avoid sleep problems, black screen etc. or follow this post.

See next section to manually fix this issue if you have accidentally installed this patch. Best option is reinstalling Catalina from the scratch!!

Status 05/07/2021:
  • DRM is known to work and you can watch Apple TV and Netflix on your iMac with AMD GPU, only.
  • use gibMacOS (download code on green button and read the online docs) to download the latest and last full Catalina installer (19H05). A complete installation recipe has been published here...
  • (using NVIDIA GPU) the Intel H.264 iGPU acceleration is still working on the 2011 models
  • (having a 2011 system) installing @dosdude1 and later sleep patches found on post #1
  • (having a 2009 and 2010 system) disable auto install patches in advance otherwise the legacy video patch make the fresh installation unusable
  • security upgrades using the @jackluke OTAfix trick (latest Beta security upgrade is 19H505)

After every MacOS update only when using a @dosdude1 patcher you will have to do the patching explained here to avoid common problems, again. Installing kernel extensions to the system is not an easy task. A complete installation guide to do this has been published (see link below with Q2). You can do this using the provided installer packages, using some tools or using the terminal and command line.

Q1: I get a black or blank screen on boot, how to fix?

A: Sierra and later has been causing "black screen" issues for many folks. This is caused by a lack of kext initialization due to a lacking board-id in the AppleGraphicsControl.kext (short AGC). A patched AGC kext and a further explanation can be found HERE, thanks to @highvoltage12v. Please look and the next question and link to get the installation guide, needed. Using some Nvidia cards in late 2009 iMac causes extra pain. The internal LCD will come up only after installing the patched AGC and booting into the newly patched MacOS. The BIOS versions will need a fix to come around this additional problem.

Q2: Sleep is broken and QuickSync is not working on my iMac 2011 in Mojave and Catalina, how do I fix this?

: Solution for Mojave and Catalina, the SandyBridge kexts are missing. Installing them fixes sleep, but causes extended boot times. @highvoltage12v has provided the needed patches containing the SandyBridge kexts in THIS POST which can be installed. You can also simply install this Catalina package or this Mojave package.

Q3: After installing Catalina on my Late 2009/2010 iMac my animations are broken/choppy, the Dock is grey and the menu bar isn't translucent. How do I fix this?

A: The @dosdude1 installer automatically executes the "Legacy Video Card Patch" leaving Late 09/2010 MXM swapped users with broken/choppy animations. If you did install Catalina and would like to manually reinstall the stock Kexts and Frameworks, a guide has been written by @highvoltage12v to manually overwrite the patched files with stock files. Another more easy fix is the reinstallation of Catalina with auto-patching disabled.

You will find a short but hopefully comprehensive plan of the complete process in this post #14900. It included also a tools section.

You may face all kind of hardware problems while and after assembling your iMac again. There is an incomplete list of common (hardware) problems including the links to the original Apple iMac Technician Guides (iMac or more apple hardware) to trouble shoot such problems. You might use Apple Hardware Test (AHT) or Apple Service Diagnostics (ASD) to check your hardware.

Some other possible modifications as USB3 or WiFi/BT 4.x replacements may interfere with a new GPU.

Please understand that we cannot remotely repair or identify broken hardware. And there is no proof possible that hardware is broken. Do not ask for one. You may likely buy a dead used card. Check it before!

And this thread is not a support organisation for sellers of dead GPU cards. Do not abuse this thread and the people spending their time here to answer and help, please just get a replacement for your dysfunctional card!

1. OpenGL

OpenGL performance can be measured using the free Unigine Valley. Use these standard settings as resolution of 1920x1080, quality Medium, stereo 3D disabled, Anti-aliasing Off to compare results.

2. Metal

Metal has been introduced in 2012 hardware (HD4000 and NVidia GPU). Use GeekBench5 Metal or the more meaningful MetalBench software (Catalina and later).

Table of Benchmark Software and upload and result forms

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

Here a list of related external projects:
  • MXM carrier board with PCI extender to plug in an eGPU into 27 Late 2009-2011 iMacs
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.
  • 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!)
  • add support for Early 2009 iMac10,1 models with MXM slot (done for 27 iMac10,1)
  • add support for AMD GCN cards (M4000, WX5170M/M5100, W6170M/M6000/M6100, and more). These will not offer VideoToolbox Support for Video Editing (4K HEVC and 4K H.264) but may will be more future proof than NVIDIA Kepler cards. Most of these cards break sleep/wake in iMac12,x (mid 2011) and cause NVRAM corruption. Needs an NVRAM/PRAM reset on each boot!
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) (card hardware or iMac BIOS issue)
  • AMD GCN GPU break sleep on iMac12,x systems (while Ubuntu Linux supports sleep/wake using these GPU type, so this is clearly a macOS issue).
  • some AMD GCN GPU have problems to sync with external displays (need display sleep to sync)
  • wire-mod replacement (enables backlight automatically unless macOS software generates PWM signal for backlight)


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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macrumors 6502
Apr 22, 2009
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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macrumors regular
May 20, 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.

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.


macrumors regular
Original poster
Aug 18, 2012
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 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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macrumors regular
Original poster
Aug 18, 2012
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.


macrumors G4
Mar 20, 2003
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. :)


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

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


macrumors regular
Original poster
Aug 18, 2012
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.


macrumors newbie
Jun 24, 2013
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.

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macrumors newbie
Jun 24, 2013
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?


macrumors newbie
Jul 12, 2013
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 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 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.


macrumors 6502a
Feb 25, 2013
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.
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macrumors 6502
May 15, 2011
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?


macrumors 601
Sep 15, 2006
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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Jan 12, 2012
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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