It's a 24" model so it has LVDS right?
I used M5100-EnableGop91-LVDS.rom
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iM 4,1-14,4 2011 iMac Graphics Card Upgrade
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I used M5100-EnableGop91-LVDS.rom
If you've tried every thing, The GPU is faulty. For a maybe temporary fix, you can reflow the gpu using an oven at 190°C (375°F) for 10 - 12 minutes.. Good luck tho
First time commenting. :3
AMD RX5500-XT 4GB (Micron) Support
***Backlight turns on after booting from OCLP then booting from an install USB with sequoia. Backlight turns on after Sequoia starts loading from USB and works correctly through the entire install process. When rebooting using OCLP and then booting from internal SSD with Sequoia installed, backlight does not turn on. It will need a backlight mod as found here.
I have three used Rx5500xt that will be flashing and modifying three pipe heat sinks and putting them into three different 12,2 imacs. I will post pictures after the heat sinks are modified, as of right now here is an original .rom and high qual pics....
Before flashing my first card, I got a P/N mismatch, but i overrode the flash and the program reported success using RX5500XT-EnableGop.rom from GitHub by @Ausdauersportler EFI-BootScreen and instructions for override from: AMD GPU Flash Guide and Here to override and unlock card . After I reinstalled the card to 12,2 iMac with an i7 2600 CPU, and it did not work due to different ram type and P/N (micron in this case).
****A new rom was made, labeled: RX5500XT-4GB-EnableGop_14.rom which works in conjunction with OCLP to give you backlight.****
ram type i think is micron as well (see pics, the bios used in GRML is for Samsung i think) is this something @dosdude1 would know how to patch?
With a working GOPEnable rom the iMac was able to blindly boot with a install image on a usb (sequoia) using the emergency OCLP boot disc instructions OCLP rescue CD. It looks like a backlight mod is needed to turn the LCD on before the OS boots. SO this means there is no Open Core boot picker, or native boot picker (holding option key at startup). BUT! once OS is booted the screen comes on... more testing needed right now but this is very promising!!!
There will be a link for a way to order the backlight mod from pcbway shortly....
PS... There are over a hundred of these cards available on aliexpress right now as of 7-30-2025... very worth picking one up if this GOP flash works...
| Type | ident | device-id | working |
|---|---|---|---|
| Green PCB | SH1494V-0 E248779 | 7340 | YES |
| iMac model | RX5500-XT_EnableGOP (micron) | needs backlight mod? | Heat Pipe Mod |
|---|---|---|---|
| 12,2 2011 27" | WORKS RX5500XT-4GB-EnableGop_14.rom | Yes, no boot screens*** | 3-pipe mxm B |
| 12,1 2011 21.5" | NO | ||
| 11,3 2010 27" | works (untested) | 3-pipe mxm-B | |
| 11,2 2010 21.5" | NO | ||
| 11,1 2010 27" | works, needs EG2 and MB mod firmware (untested) | 3-pipe MXM-B |
***Backlight turns on after booting from OCLP then booting from an install USB with sequoia. Backlight turns on after Sequoia starts loading from USB and works correctly through the entire install process. When rebooting using OCLP and then booting from internal SSD with Sequoia installed, backlight does not turn on. It will need a backlight mod as found here.
I have three used Rx5500xt that will be flashing and modifying three pipe heat sinks and putting them into three different 12,2 imacs. I will post pictures after the heat sinks are modified, as of right now here is an original .rom and high qual pics....
Before flashing my first card, I got a P/N mismatch, but i overrode the flash and the program reported success using RX5500XT-EnableGop.rom from GitHub by @Ausdauersportler EFI-BootScreen and instructions for override from: AMD GPU Flash Guide and Here to override and unlock card . After I reinstalled the card to 12,2 iMac with an i7 2600 CPU, and it did not work due to different ram type and P/N (micron in this case).
****A new rom was made, labeled: RX5500XT-4GB-EnableGop_14.rom which works in conjunction with OCLP to give you backlight.****
Code:
Old SSID: 2401
New SSID: 2401
Old P/N: 113-EM24G4G-007 <-----looks like a 4GB? Has micron ram as well...
New P/N: 113-EM24G8G-S00
The result of RSA signature verify is PASS.
Old DeviceID: 7340
New DeviceID: 7340
Old Product Name: NAVI14 Gaming XTX A1 K9409QCA.CLB 2020 2333/14974
New Product Name: NAVI14 Gaming XTX A1 K9A12QCA.SLB 2020 2333/14974
Old BIOS Version: 017.002.000.000.000000
New BIOS Version: 017.002.000.000.000000
Flash type: GD25Q80C/E
Burst size is 256
100000/100000h bytes programmed
100000/100000h bytes verifiedram type i think is micron as well (see pics, the bios used in GRML is for Samsung i think) is this something @dosdude1 would know how to patch?
With a working GOPEnable rom the iMac was able to blindly boot with a install image on a usb (sequoia) using the emergency OCLP boot disc instructions OCLP rescue CD. It looks like a backlight mod is needed to turn the LCD on before the OS boots. SO this means there is no Open Core boot picker, or native boot picker (holding option key at startup). BUT! once OS is booted the screen comes on... more testing needed right now but this is very promising!!!
There will be a link for a way to order the backlight mod from pcbway shortly....
PS... There are over a hundred of these cards available on aliexpress right now as of 7-30-2025... very worth picking one up if this GOP flash works...
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This post is only meant for people using an AMD GCN 1-3 card in 2011 iMac12,x models regardless of all the warnings we have put into the documentation. Due to some unknown reasons the wake process after sleep or deep sleep runs very often into a timeout and the system stuck with a black screen. On the next reboot you cannot boot straight into the EFI boot picker or any macOS without forcing the PRAM reset in advance. This is an annoying feature.
User @grosmario figured out recently that sometimes the IORegistry of those iMac12,x models with GCN 1-3 cards show different and conflicting values in the GFX0 section, in particular both the
You can try to force the (presumably) correct entries in the OpenCore configuration file (config.plist) by adding these four lines for the green W5170M card in the DeviceProperties section right before the line containing the
Most likely only these two lines for the
I know, those changes forces you to edit the OCLP supplied OpenCore configuration file named config.plist hidden in the EFI partition using a text editor or better a plist/XML editor like ProperTree.
Please let the community know if those changes make a difference on your GCN 1-3 equipped iMac12,x. I cannot test lacking both proper hardware and time.
Thanks in advance!
User @grosmario figured out recently that sometimes the IORegistry of those iMac12,x models with GCN 1-3 cards show different and conflicting values in the GFX0 section, in particular both the
class-code and compatible entries.You can try to force the (presumably) correct entries in the OpenCore configuration file (config.plist) by adding these four lines for the green W5170M card in the DeviceProperties section right before the line containing the
agdpmod entry:
Markdown (GitHub flavored):
<key>class-code</key>
<data>AAADAA==</data>
<key>compatible</key>
<string>pci103c,810a", "pci1002,6820", "pciclass,030000", "GFX0</string>Most likely only these two lines for the
class-code may or can make the difference for all GCN1-3 cards when being installed in iMac12,x systems from 2011, i.e. this might cover the M4000, M5100, W6170M, M6000, M6100, S7100X, W7170M cards as well.
Markdown (GitHub flavored):
<key>class-code</key>
<data>AAADAA==</data>I know, those changes forces you to edit the OCLP supplied OpenCore configuration file named config.plist hidden in the EFI partition using a text editor or better a plist/XML editor like ProperTree.
Please let the community know if those changes make a difference on your GCN 1-3 equipped iMac12,x. I cannot test lacking both proper hardware and time.
Thanks in advance!
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the "ident" should be SH149V-0 E248779 according to your pictures, notSH149V-0 E248799...
I can comfirm that the second M5100 I've ordered works great. It has SK Hynix vram so after flashing the correct firmware everything works as expected on my iMac 9,1
EDIT: Except for brightness control? is this a known issue? can't be controlled.
EDIT2: It does seem to overheat. It shut down randomly and after restarting it didn't get very far. I've placed a copper shim as instructed yet it still seems to overheat? Time to open it up again...
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When I had my 5100, i ran smc fan control with a temp set to be lower on the gpu side, so the fan ran at a higher speed instead of stock.. i highly recommend a .5cm copper sink on the die, as well as the correct size gpu pads (.5-2mm) for all the ram and voltage regulators... i use thermal grizzly for everything (a bit pricey but worth it)... otherwise congrats on giving the old mac a new life!
Hello!
I’ve got a problem with my iMac 21,5 2011 and Nvidia Quadro K1100M.
I replaced standard graphic card and now when I start up I have a black screen. When I start up with the Option key pressed, a selection menu appears where I can choose Mac OS or Recovery, both menus start loading if I press them, and then artifacts appear on the screen and the system stops loading
What can I do?
I’ve got a problem with my iMac 21,5 2011 and Nvidia Quadro K1100M.
I replaced standard graphic card and now when I start up I have a black screen. When I start up with the Option key pressed, a selection menu appears where I can choose Mac OS or Recovery, both menus start loading if I press them, and then artifacts appear on the screen and the system stops loading
What can I do?
Artifact = Bad card or wrong vBIOS.
Even after flashing the correctly modified vBIOS, you still need to press Option each time you power up your iMac to get to the boot menu. Fix this (after flashing vBIOS) by installing OCLP.
Could also be an overheat issue if your heatsink isn’t installed well….