iM 4,1-14,4 2011 iMac Graphics Card Upgrade

[KennyW]

Done my mod last night after the second 6790m failed to work. I have replace the original bad 6790m with another 6790m a year ago. The second 6790m decided to rest in peace after one year, so now got myself a K5100M.
Also upgrade the CPU to i7-2600 3.4Ghz, the old CPU was a i5-2400 3.1Ghz.
Flashed the rom with SSH, everything went smooth. The new K5100M and the i7 CPU works like a charm.
I am staying with High Sierra at the moment, just to make sure everything stable.
Expected boot screen and screen brightness is working, sleep also works fine.
I am planning to move to Mojave later, so question is, is the sleep problem only occurs in Mojave and later OS? Because now seems fine with High Sierra. I didn't do any software patch or mod except flashing vbios.
I also use the original X bracket that come with the K5100M, just drill the holes to fit the screws.
Big thanks to nikey22 for the custom bios and xanderon for the SSH method.

Des.
View attachment 1700108

View attachment 1700109
View attachment 1700111

Unless you have specific reason to run Mojave, I would suggest to go directly to Catalina with the well designed DosDude1 Catalina Patcher. Your K5100 should run decently, but remember to disable SIP first in your setup.

And always keep a copy of your natively supported High Sierra in your default active partition that would launch on PRAM reset. It will save you many troubles in the future.

 

[Kaapo Tupas]

Hyvää Joulua!

I just updated the Ausdauersporlers iMac 2011 Catalina Patcher after I uptdated with Dosdude from 10.15.3 to 10.15.7.

After the Dosdude update, I got black screen with iMac 2011 (with nVidia Nicks vBios 780M 4gb). TV worked fine with HDMI. With Ausdauersportlers iMac 2011 Catalina patcher I got the screen working right away. Thanks again for the magnificent job.

btw. This time I just ran Dosdude without usb... worked fine - (if black screen not counted). But yes, the final patcher was a right Christmas gift for me. Thanks from Finland. Danke schön und Ich wünchen Sie Gutes Weihnacten.

Snow came today. So did christmas.

 

[Audiologist1974]

Unless you have specific reason to run Mojave, I would suggest to go directly to Catalina with the well designed DosDude1 Catalina Patcher. Your K5100 should run decently, but remember to disable SIP first in your setup.

And always keep a copy of your natively supported High Sierra in your default active partition that would launch on PRAM reset. It will save you many troubles in the future.

Thanks for the advice. I still using 32bit software, so Catalina is a no go yet.

 

[mheathcote]

unpatch using patch-kext.sh -u, reboot, patch again using patch-kext.sh —ns and reboot.

Legend! This worked perfectly.

I wiped everything and started fresh as the previous install was Big Sur 11.0.1 and I'd copied across data from my HighSierra partition - although this worked, I did find the copying across all the old apps etc made Big Sur to be really slow, so I decided to do a full fresh install.

Some notes:
Used OC 0.6.4 - I tried with 0.6.5pre but had repeated panics and it never completed the setup.
Once setup was complete and before Setup Assistant I needed to run the patch-kexts.sh --2010 to prevent kernel panics. (somehow I didn't need to do this with Big Sur 11.0.1)
After setup was complete I didn't have any external monitor support, but after running the above re-patching it worked perfectly.

Maybe it's due to the fresh install, or maybe it's the new Metal GUI, but Big Sur feels really really quick and smooth on this setup now.

Thanks for all your efforts.

 

[Ausdauersportler]

Legend! This worked perfectly.

I wiped everything and started fresh as the previous install was Big Sur 11.0.1 and I'd copied across data from my HighSierra partition - although this worked, I did find the copying across all the old apps etc made Big Sur to be really slow, so I decided to do a full fresh install.

Some notes:
Used OC 0.6.4 - I tried with 0.6.5pre but had repeated panics and it never completed the setup.
Once setup was complete and before Setup Assistant I needed to run the patch-kexts.sh --2010 to prevent kernel panics. (somehow I didn't need to do this with Big Sur 11.0.1)
After setup was complete I didn't have any external monitor support, but after running the above re-patching it worked perfectly.

Maybe it's due to the fresh install, or maybe it's the new Metal GUI, but Big Sur feels really really quick and smooth on this setup now.

Thanks for all your efforts.

Fine,

I do not understand why this „intermediate„ patching was necessary, but why not stopping the setup pressing alt q, booting straight into USB again and run the patch-kext.sh from there.

The 0.6.5pre need to be tested....had no time but the bricked iMac story drives us mad.

Frohe Weihnachten!

Edit:
There is a special config file only for installation of Big Sur to be used until patching has been finished. Before the last reboot to activate patches switch the config file back to your NVIDIA/AMD specific version.

 

[StephN999]

Bonjour,

I finally got today my AMD WX4150 card, I flash it with the bios I got from TechPowerUp (Gop updated by the way), my iMac boot with the latest OpenCore provided here, I have a display after almost a minute on my external screen, nothing on the internal, just the Shell Efi and ResetNVRAM option displayed, I don't go further (the fans are at full speed).

Well I'm happy on one point is that there is a display, it's reassuring, now, I'm going to read the tutorial again, either I missed something, or my EFI mod and the bios of the card I use is a problem.

In any case I repeat it is reassuring, otherwise to my surprise the PCB was blue (HP?) and the reference written on the board "109-C98581-10_02".

See you later.

Edit: tested without HDD/SSD but with an unpatched key from Big Sur 11.1 Installer.

 

[KennyW]

Bonjour,

I finally got today my AMD WX4150 card, I flash it with the bios I got from TechPowerUp (Gop updated by the way), my iMac boot with the latest OpenCore provided here, I have a display after almost a minute on my external screen, nothing on the internal, just the Shell Efi and ResetNVRAM option displayed, I don't go further (the fans are at full speed).

Well I'm happy on one point is that there is a display, it's reassuring, now, I'm going to read the tutorial again, either I missed something, or my EFI mod and the bios of the card I use is a problem.

In any case I repeat it is reassuring, otherwise to my surprise the PCB was blue (HP?) and the reference written on the board "109-C98581-10_02".

See you later.

Edit: tested without HDD/SSD but with an unpatched key from Big Sur 11.1 Installer.

It is normal to have only the external display active for the PC GOP vBIOS.
The same occurred with my WX4130 and RX480.
The internal display would light up with the Mac vBIOS flashed, but only when the OSX driver loaded.
You won't have boot screen with the released vBIOS, unless you use OC.

 

[Tomvreugdenhil]

I want to thank the whole forum because I upgraded my 27" iMac 2011 from a dead 6970M to a 770M and installed a new VBIOS. I recorded my process and made a video about it including teardown and flashing. Maybe it is of interest to someone else reading through this forum: 2011 27" iMac GPU 770M

 

[Pascal Baillargeau]

Bonjour,

I finally got today my AMD WX4150 card, I flash it with the bios I got from TechPowerUp (Gop updated by the way), my iMac boot with the latest OpenCore provided here, I have a display after almost a minute on my external screen, nothing on the internal, just the Shell Efi and ResetNVRAM option displayed, I don't go further (the fans are at full speed).

Well I'm happy on one point is that there is a display, it's reassuring, now, I'm going to read the tutorial again, either I missed something, or my EFI mod and the bios of the card I use is a problem.

In any case I repeat it is reassuring, otherwise to my surprise the PCB was blue (HP?) and the reference written on the board "109-C98581-10_02".

See you later.

Edit: tested without HDD/SSD but with an unpatched key from Big Sur 11.1 Installer.

Make sure you can access this mac with teamviewer on windows 10 and Mac OS, without password, for login in OS and in teamviewer is a must. Then you will be able to flash vbios remotely through windows 10.
Happy christmas StephN999!

 

[davidg5678]

Hello,

This is my first post here on MacRumors. Before I ask some questions about my computer, I would really like to thank everyone here for their hard work upgrading these iMacs and documenting the process online.

I have a 27" Mid-2010 iMac that I am trying to upgrade with a WX4150 GPU. I know that support for this particular card is said to be spotty, but since I saw that some other people (also without 2011 iMacs) reported success, I thought that I would give it a try. For the purposes of documentation, I have attached some high-resolution scans of the GPU I purchased, so that others can see exactly what it looks like. This is an HP card with the model number is 109-C98581-10_02, similar to the one mentioned a few posts above.

I was able to physically replace the ATI 5750 card inside my iMac with the WX4150. I used some 1.5mm thermal pads to bridge the gaps between the GPU die/VRAM and the heatsink. I did not want to risk the possibility of short circuits, so I decided to cover several key areas of the GPU with Kapton tape to reduce the risks. I reassembled the computer and I used the Xanderon Linux USB along with amdvbflash to reflash the VBIOS with the latest one from the first post of this thread. (To be more precise, I used the VBIOS labeled "Dell RX 560 4GB.ROM")

Reflashing the VBIOS over SSH seemed to be successful, so I rebooted the computer, only to be faced with the dreaded black screen. (Before you mention them: I have thoroughly read over the first post in the thread along with the troubleshooting posts several times. I also searched the entire thread for everything WX4150-related and I read all of the corresponding posts.) At this point, my drives were all internally disconnected, (as I was using the Linux USB) but I decided I would reattach my SSD to see if perhaps I could still access macOS 10.13 albeit without a boot screen. Unfortunately, this is where I ran into some trouble.

For some reason, when I have the WX4150 installed, the computer outright refuses to turn on when internal drives are also connected to SATA power. Disconnecting the drives when the GPU is installed allows the computer to chime and turn on (to a black screen), and removing the GPU allows the computer to turn on with drives connected. If I reinstall the ATI 5750 and my SSD, the computer still boots normally, including with a functional LCD. These symptoms lead me to believe that there may be a short to ground happening when the WX4150 is installed. I smothered the entire GPU with even more Kapton tape, to see if I could at least confirm my suspicions of a short, but the issues I was experiencing persisted.

I have reverted the computer to its stock configuration, and it is now working normally, but I would obviously still love to get the WX4150 to work. I am curious if anyone has experienced similar issues before and was able to resolve them. Any help or advice would be greatly appreciated.

Thank you!

 

[Pascal Baillargeau]

Hello,

This is my first post here on MacRumors. Before I ask some questions about my computer, I would really like to thank everyone here for their hard work upgrading these iMacs and documenting the process online.

I have a 27" Mid-2010 iMac that I am trying to upgrade with a WX4150 GPU. I know that support for this particular card is said to be spotty, but since I saw that some other people (also without 2011 iMacs) reported success, I thought that I would give it a try. For the purposes of documentation, I have attached some high-resolution scans of the GPU I purchased, so that others can see exactly what it looks like. This is an HP card with the model number is 109-C98581-10_02, similar to the one mentioned a few posts above.

I was able to physically replace the ATI 5750 card inside my iMac with the WX4150. I used some 1.5mm thermal pads to bridge the gaps between the GPU die/VRAM and the heatsink. I did not want to risk the possibility of short circuits, so I decided to cover several key areas of the GPU with Kapton tape to reduce the risks. I reassembled the computer and I used the Xanderon Linux USB along with amdvbflash to reflash the VBIOS with the latest one from the first post of this thread. (To be more precise, I used the VBIOS labeled "Dell RX 560 4GB.ROM")

Reflashing the VBIOS over SSH seemed to be successful, so I rebooted the computer, only to be faced with the dreaded black screen. (Before you mention them: I have thoroughly read over the first post in the thread along with the troubleshooting posts several times. I also searched the entire thread for everything WX4150-related and I read all of the corresponding posts.) At this point, my drives were all internally disconnected, (as I was using the Linux USB) but I decided I would reattach my SSD to see if perhaps I could still access macOS 10.13 albeit without a boot screen. Unfortunately, this is where I ran into some trouble.

For some reason, when I have the WX4150 installed, the computer outright refuses to turn on when internal drives are also connected to SATA power. Disconnecting the drives when the GPU is installed allows the computer to chime and turn on (to a black screen), and removing the GPU allows the computer to turn on with drives connected. If I reinstall the ATI 5750 and my SSD, the computer still boots normally, including with a functional LCD. These symptoms lead me to believe that there may be a short to ground happening when the WX4150 is installed. I smothered the entire GPU with even more Kapton tape, to see if I could at least confirm my suspicions of a short, but the issues I was experiencing persisted.

I have reverted the computer to its stock configuration, and it is now working normally, but I would obviously still love to get the WX4150 to work. I am curious if anyone has experienced similar issues before and was able to resolve them. Any help or advice would be greatly appreciated.

Thank you!

Hi,
Do you use Opencore?

 

[davidg5678]

Hi,
Do you use Opencore?

Thanks for your reply. I am using a stock installation of High Sierra right now, without OpenCore. I figured that upgrading beyond 10.13 should wait until everything else is working.

If I am not mistaken, you have had some success with the WX4150 in your 21" 2010 iMac, right? Your post a few weeks ago inspired me to try this card out in my 27" model. Did you have any problems with getting the GPU working?

 

[Pascal Baillargeau]

Thanks for your reply. I am using a stock installation of High Sierra right now, without OpenCore. I figured that upgrading beyond 10.13 should wait until everything else is working.

If I am not mistaken, you have had some success with the WX4150 in your 21" 2010 iMac, right? Your post a few weeks ago inspired me to try this card out in my 27" model. Did you have any problems with getting the GPU working?

You will not have a display on internal LCD without Opencore with flashed GOP vbios.

 

[gnommak]

Hi everyone,
I am having some issues when I upload the kext files to repair the sleep mode and brightness control on my 2011 27in iMac running dos dudes patcher Catalina. I have downloaded the kext files from Curtis Gross's youtube. I am successful installing the Catalina Os and it runs flawless, however when I upload the kext files through opencore hackintool they install fine and I restart my computer. When I restart and select my drive, because I am booting off my new SSD externally and the computer begins to boot. The progress bar reaches half way and the computer restarts by itself. I hold down option to select my drive again, restart the booting process into the Catalina SSD the progress bar reaches halfway and restarts by itself. I can not get my computer to reboot into Catalina after I install the kext files. Has anyone experienced this issue yet, and if so do you by chance have a remedy to resolve this issue.

Thank you
Best regards,
Brad O.

You have installed Mojave sleep kexts. I have made same mistake. This cause reboot loop.
Start you mac holding shift key and delete all installed kexts. Go to first post and find all links about sleep.
In one of them you will find kexts for Catalina. Install them. Thats all

 

[KennyW]

Hello,

This is my first post here on MacRumors. Before I ask some questions about my computer, I would really like to thank everyone here for their hard work upgrading these iMacs and documenting the process online.

I have a 27" Mid-2010 iMac that I am trying to upgrade with a WX4150 GPU. I know that support for this particular card is said to be spotty, but since I saw that some other people (also without 2011 iMacs) reported success, I thought that I would give it a try. For the purposes of documentation, I have attached some high-resolution scans of the GPU I purchased, so that others can see exactly what it looks like. This is an HP card with the model number is 109-C98581-10_02, similar to the one mentioned a few posts above.

I was able to physically replace the ATI 5750 card inside my iMac with the WX4150. I used some 1.5mm thermal pads to bridge the gaps between the GPU die/VRAM and the heatsink. I did not want to risk the possibility of short circuits, so I decided to cover several key areas of the GPU with Kapton tape to reduce the risks. I reassembled the computer and I used the Xanderon Linux USB along with amdvbflash to reflash the VBIOS with the latest one from the first post of this thread. (To be more precise, I used the VBIOS labeled "Dell RX 560 4GB.ROM")

Reflashing the VBIOS over SSH seemed to be successful, so I rebooted the computer, only to be faced with the dreaded black screen. (Before you mention them: I have thoroughly read over the first post in the thread along with the troubleshooting posts several times. I also searched the entire thread for everything WX4150-related and I read all of the corresponding posts.) At this point, my drives were all internally disconnected, (as I was using the Linux USB) but I decided I would reattach my SSD to see if perhaps I could still access macOS 10.13 albeit without a boot screen. Unfortunately, this is where I ran into some trouble.

For some reason, when I have the WX4150 installed, the computer outright refuses to turn on when internal drives are also connected to SATA power. Disconnecting the drives when the GPU is installed allows the computer to chime and turn on (to a black screen), and removing the GPU allows the computer to turn on with drives connected. If I reinstall the ATI 5750 and my SSD, the computer still boots normally, including with a functional LCD. These symptoms lead me to believe that there may be a short to ground happening when the WX4150 is installed. I smothered the entire GPU with even more Kapton tape, to see if I could at least confirm my suspicions of a short, but the issues I was experiencing persisted.

I have reverted the computer to its stock configuration, and it is now working normally, but I would obviously still love to get the WX4150 to work. I am curious if anyone has experienced similar issues before and was able to resolve them. Any help or advice would be greatly appreciated.

Thank you!

Do you have record or photo of the Terminal output during flashing in Linux ?
It may give hints whether the flashing is really successful or not.

Secondly, if there is no chime sound on installing the new GPU and power-on, that means the card is not POSTing.
The reason is unknown for some combination of iMacs and GPUs, unless your card is defective.
There is no rescue at the moment if no POSTing.

If the flashing is successful and the GPU is working and there is a chime sound on power-on, the internal display should be on after a minute or so when the OSX driver is loaded.

Depending on the version of High Sierra, an earlier one requires the AppleGraphicsControl.kext patched with your iMac Board ID to enable the internal display. It seemed the later versions have corrected that.

For the HP version of WX4150, some users reported the need of an active miniDP adapter for external display to activate the internal display.

 

[Nguyen Duc Hieu]

I was able to physically replace the ATI 5750 card inside my iMac with the WX4150. I used some 1.5mm thermal pads to bridge the gaps between the GPU die/VRAM and the heatsink. I did not want to risk the possibility of short circuits, so I decided to cover several key areas of the GPU with Kapton tape to reduce the risks. I reassembled the computer and I used the Xanderon Linux USB along with amdvbflash to reflash the VBIOS with the latest one from the first post of this thread. (To be more precise, I used the VBIOS labeled "Dell RX 560 4GB.ROM")

Thank you!

@davidg5678​

I couldn't flash the Dell BIOS to my HP WX4150 4GB in Windows with Atiwinflash. Yes, your card looks exactly the same as mine.

I used the vBIOS in post #4921
It was linked from Post #1 as the ROM for WX4170.
Linux flash method and CH341a programer let you forceflash the vBIOS, even when it's not compatible.
Atiwinflash check and only let you flash if the vBIOS is compatible.

With this VBIOS flashed to the HP card, on my iMac 2010 the following occure (with stock High Sierra, no kext injected at all)
1. Single Display Mode => Total black-out
2. Target Display Mode => full screen display (I use a DisplayPort to miniDisplayPort cable, no adapter/converter)
3. Target Display Mode then switch back to normal => Internal screen shows image
4. Dual display set-up with real external monitor=> Both screens show image
5. Dual display set-up with a VGA dummy plug => Internal screen shows image, but black-out time is long.

With the Catalina Loader SD card (refer to post #1 for how-to-make) + High Sierra
1. Single Display Mode => Boot picker screen work, then black-out.
2, 3, 4, 5 => same, but with boot picker screen. black-out time in 5. is roughly 10s (probably the iMac tries to guess what kind of display the VGA dummy plug is simulating)
for 5. I use one mDP to VGA adapter + one VGA dummy plug.

With the Catalina Loader, I could install Windows 10 64bit to the second SSD inside the iMac using the USB installer, Boot Camp drivers (5,1) were installed without any hiccup.

Hope my description help with your case.

​

 

[KennyW]

I want to thank the whole forum because I upgraded my 27" iMac 2011 from a dead 6970M to a 770M and installed a new VBIOS. I recorded my process and made a video about it including teardown and flashing. Maybe it is of interest to someone else reading through this forum: 2011 27" iMac GPU 770M

I can see that changing the GPU is a really complex procedure in iMac 2011 as compared to my iMac 2010 which requires only removing 3 screws that hold the GPU, and are accessible once the LCD panel is opened up without the need to take out the logic board.

 

[MirComputers]

Done my mod last night after the second 6790m failed to work. I have replace the original bad 6790m with another 6790m a year ago. The second 6790m decided to rest in peace after one year, so now got myself a K5100M.
Also upgrade the CPU to i7-2600 3.4Ghz, the old CPU was a i5-2400 3.1Ghz.
Flashed the rom with SSH, everything went smooth. The new K5100M and the i7 CPU works like a charm.
I am staying with High Sierra at the moment, just to make sure everything stable.
Expected boot screen and screen brightness is working, sleep also works fine.
I am planning to move to Mojave later, so question is, is the sleep problem only occurs in Mojave and later OS? Because now seems fine with High Sierra. I didn't do any software patch or mod except flashing vbios.
I also use the original X bracket that come with the K5100M, just drill the holes to fit the screws.
Big thanks to nikey22 for the custom bios and xanderon for the SSH method.

Des.
View attachment 1700108

View attachment 1700109
View attachment 1700111

Remember you can oven the original cards, undervolt with bios modding and they will not fail again - this is what i do for people happy with High Sierra - https://www.pizzaundervolt.com/2020/12/25/imac-gpu-undervolt/

 

[MirComputers]

Dear Ausdauersportler,

thank you for taking the time to answer.

Unfortunately, this is the third time you answer me with something like "you haven't read the first post, you should have looked around before posting, and anyway please find the solution by yourself as I did before you".

While actually in all of the occasions I had read the first post, I had looked around before posting, and if I decided to post, then you know?, it was just because I found no solution anywhere, and I hoped that there were people out there with more experience than me who were willing to help (otherwise, what this forum would be for?), instead of spending their time trolling newbies.

So at the end of the day your answers were empty presumption (presumption that, say, for sure I had not done my homework in advance): nothing less, nothing more. Adding no value to find a real solution for problems (or even simple doubts) that had never been tackled before.

[If I'm wrong, and you can provide a link to a post explaining exactly how to solve my specific issue with ROMtool, for instance, I will be glad to apologize of course. I was not able to find it.]

Finally, let me remark that if there is one who is posting without reading first, that seems to be you, since in all cases you overlooked important pieces of information that I posted regarding my specific situations.

Not sure whether you are doing all of this with the best intentions, or what. And maybe I was just unlucky in my interactions with you, while 99% of the time you provide brilliant solutions to everybody. But I find all of your answers to my posts to be very dysfunctional: they make people (yourself, in the first place, but of course also me and everybody else who is scrolling through the forum looking for real answers and solutions) waste a lot of time; and above all I think they deter other people from posting answers that could actually add some real value and help come up with real solutions.

So please, from now on, may I kindly ask you to ignore my posts? This is exactly what I will be doing with yours, whatever you may write in the future. Hope we can find this agreement.

Thank you

Sergio

100% spot on. Not just you my friend.

 

[geertv]

I guess you have to enter your WiFi key to connect the iMac to you home network or you connect the iMac using a cable to the router.

The other option would be to download the macOS installer you need using by using a @dosdude1 High Sierra patcher (just let it download the original apple installer) or the gibMacOS utility...

I created a bootable USB with gibMacOS for High Sierra, this is working.
Would you advice on installing Big Sur or Catalina for now ?

 

[davidg5678]

Do you have record or photo of the Terminal output during flashing in Linux ?
It may give hints whether the flashing is really successful or not.

Secondly, if there is no chime sound on installing the new GPU and power-on, that means the card is not POSTing.
The reason is unknown for some combination of iMacs and GPUs, unless your card is defective.
There is no rescue at the moment if no POSTing.

If the flashing is successful and the GPU is working and there is a chime sound on power-on, the internal display should be on after a minute or so when the OSX driver is loaded.

Depending on the version of High Sierra, an earlier one requires the AppleGraphicsControl.kext patched with your iMac Board ID to enable the internal display. It seemed the later versions have corrected that.

For the HP version of WX4150, some users reported the need of an active miniDP adapter for external display to activate the internal display.

Thanks to everyone for their replies!

Luckily, I happened to take a screenshot when I was flashing the GPU (it is attached below). This photo shows me overwriting the card after I had already flashed it once, so most of the values remain identical. It sounds like I should try flashing the GPU again with the GOP VBIOS instead of the Dell 4GB VBIOS though.

The computer did chime when the WX4150 GPU was installed, so thankfully, I think it is POSTing. I could only get the computer to POST if I unplugged my SSD from power though. Whenever both the SSD and WX4150 are installed, something in the PSU seems to trip (a protection circuit, perhaps?), which prevents the computer from POSTing. I think this is likely due to a short somewhere, so I am going to try to use even more Kapton tape.

What you have said about the OSX driver is interesting to me, as without any drives connected, I really should have never expected to see much of anything on the screen. I am going to try to use OpenCore with the GOP VBIOS and see if I can get things to work better that way. I'll also have to experiment with some Mini-Displayport/Target Display Mode related things as mentioned by @Nguyen Duc Hieu to see if they help solve the problem.

 

[Ausdauersportler]

Thanks to everyone for their replies!

Luckily, I happened to take a screenshot when I was flashing the GPU (it is attached below). This photo shows me overwriting the card after I had already flashed it once, so most of the values remain identical. It sounds like I should try flashing the GPU again with the GOP VBIOS instead of the Dell 4GB VBIOS though.

The computer did chime when the WX4150 GPU was installed, so thankfully, I think it is POSTing. I could only get the computer to POST if I unplugged my SSD from power though. Whenever both the SSD and WX4150 are installed, something in the PSU seems to trip (a protection circuit, perhaps?), which prevents the computer from POSTing. I think this is likely due to a short somewhere, so I am going to try to use even more Kapton tape.

What you have said about the OSX driver is interesting to me, as without any drives connected, I really should have never expected to see much of anything on the screen. I am going to try to use OpenCore with the GOP VBIOS and see if I can get things to work better that way. I'll also have to experiment with some Mini-Displayport/Target Display Mode related things as mentioned by @Nguyen Duc Hieu to see if they help solve the problem.

My 2 cents:

- broken SATA cable, exchange it!

- SMC got confused on GPU exchange, try a reset
- PRAM got flooded with incompatible data, get the GPU out and do three PRAM resets (even without a GPU possible)
- deinstall the front metal part and you can exchange the GPU as easy as in the 2010 without deinstalling the logic board each time. after fixing your problems you may finally install it back to fix the sink with the top right screw.

Most if not all this was already written down in the hardware problems section on post #1. I would like you to re-read it.

Get the Catalina Loader installed on an SD card / USB drive and have it ready if you can start the system. It should boot from it of you disconnect your internal SSD. So you may at least get a working display. It was clearly mentioned in the coarse plan posted on page and post #1.

 

[Carriba]

Hello everybody.
I have this problem:
I bought gpu hd6970m2g for HP workstation (checked personally). Put in my iMac - 2011 27 i7 hd6970m2g(life 50/50). With a new gpu iMac have black screen and all! On the board 2 diodes light out of 4.
Took the CH341A, downloaded bios from old 6970m(my iMac) , uploaded to new 6070m(HP), loaded successfully, but iMac have black screen and started to turn off after 2-3 min.
Download bios 6970m2g from the website :

Apple HD 6970M VBIOS

2048 MB GDDR5, 680 MHz GPU, 900 MHz Memory

www.techpowerup.com

uploaded to new 6070m(HP), loaded successfully, but iMac have black screen.
Put in my iMac old 6970m - everything is working...
??? What am I doing wrong ???
Gpu new and old 1:1 (vram samsung, chip bios Pm25LD010, number carts 109-c29647-00 )
1 photo - old gpu & new gpu
2 photo checked new gpu 6970m2g on HP

 

[Ausdauersportler]

I created a bootable USB with gibMacOS for High Sierra, this is working.
Would you advice on installing Big Sur or Catalina for now ?

Big Sur!

Some thoughts about Big Sur vs. Catalina:

Catalina:
- (using a new AMD GPU) DRM is known to work and you can watch Apple TV and Netflix on your iMac
- @dosdude1 graphical patcher can be used, but recently it became more annoying to install updates, since this patcher cannot load the most recent (19H5 and 19H114) installers and you have to use third party products. Additionally you have to boot back into the Installer USB and apply patches a last time to get everything running, again (installation to disk does not do this properly). My recipe has been published here...
- (using NVIDIA GPU) 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) or using OC with VMware settings

Big Sur:
- most recent OS and features
- most recent Xcode
- installation using the iMac micro patcher patches everything in a single step
- (using a new AMD GPU) DRM is currently broken with AMD cards (unlike Catalina) and may be restored by upcoming versions of the WhateverGreen extension (will be included into the micro patcher then)
- (using NVIDIA GPU) NO more iGPU acceleration. Possibly too much if the necessary code has been stripped from the new Big Sur kernel.
- WiFi modded systems will be supported OOB without additional software patching to enable HandOff and Continuity

 

[Ausdauersportler]

Hello everybody.
I have this problem:
I bought gpu hd6970m2g for HP workstation (checked personally). Put in my iMac - 2011 27 i7 hd6970m2g(life 50/50). With a new gpu iMac have black screen and all! On the board 2 diodes light out of 4.
Took the CH341A, downloaded bios from old 6970m(my iMac) , uploaded to new 6070m(HP), loaded successfully, but iMac have black screen and started to turn off after 2-3 min.
Download bios 6970m2g from the website :

Apple HD 6970M VBIOS

2048 MB GDDR5, 680 MHz GPU, 900 MHz Memory

www.techpowerup.com

uploaded to new 6070m(HP), loaded successfully, but iMac have black screen.
Put in my iMac old 6970m - everything is working...
??? What am I doing wrong ???
Gpu new and old 1:1 (vram samsung, chip bios Pm25LD010, number carts 109-c29647-00 )
1 photo - old gpu & new gpu
2 photo checked new gpu 6970m2g on HP

Why not using the original BIOS from YOUR Apple 6970 card??