iMac 27' Mid 2011 GPU Issue

[lastdrop]

First, apologies if cross-posting isn't allowed. Initially posted it in another thread not realizing that it's for macbook pro

My iMac (27in, Mid 2011) running Sierra (10.12.6) with AMD Radeon HD 6970 is having what it seems to be the dreaded GPU issue. Started with sudden display blue vertical lines and then being stucked in gray screen after several reboots.

So I tried disabling the dGPU by following the steps discussed in this thread:

• Reset PRAM/NVRAM
• Boot to Single User Mode
• Since I can't disable SIP in single user mode, I boot into rEFInd image and disable SIP from there
• Boot again to Single User Mode and disabled dGPU:
  

  nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=%01%00%00%00
  nvram boot-args="-v"

• Reboot
• Move the `AMDRadeonX300.kext` to another directory then reboot
  

  /sbin/mount -uw /
  mkdir -p /System/Library/Extensions-off
  mv /System/Library/Extensions/AMDRadeonX3000.kext /System/Library/Extensions-off/
  touch /System/Library/Extensions/
  reboot

It still end up with a blank gray screen after disabling gpu and moving `AMDRadeonX300.kext`. I booted again in single user mode, mounted the `/` as writable and moved all `AMD*` from /System/Library/Extension to another directory. These are the files that were moved:

drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMD2400Controller.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMD2600Controller.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMD3800Controller.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMD4600Controller.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMD4800Controller.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMD5000Controller.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMD6000Controller.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMD7000Controller.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMD8000Controller.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMD9000Controller.kext
drwxr-xr-x@  3 root  wheel   102 16 Jun  2017 AMD9500Controller.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMD9510Controller.kext
drwxr-xr-x@  3 root  wheel   102 16 Jun  2017 AMD9515Controller.kext
drwxr-xr-x@  3 root  wheel   102 16 Jun  2017 AMD9520Controller.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMDFramebuffer.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMDLegacyFramebuffer.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMDLegacySupport.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMDMTLBronzeDriver.bundle
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMDRadeonVADriver.bundle
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMDRadeonX3000.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMDRadeonX3000GLDriver.bundle
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMDRadeonX4000.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMDRadeonX4000GLDriver.bundle
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMDRadeonX4100.kext
drwxr-xr-x@  3 root  wheel   102 16 Jun  2017 AMDRadeonX4150.kext
drwxr-xr-x@  3 root  wheel   102 16 Jun  2017 AMDRadeonX4200.kext
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMDShared.bundle
drwxr-xr-x@  3 root  wheel   102 28 Apr  2017 AMDSupport.kext

This time it booted properly, I was able to login and I'm using it right now. Of course the graphics rendering is very slow (animations are slow to render with flickering) but everything else (audio, network) looks fine. I was able to do a Time Machine backup and restarted twice.

Checking the System Report shows that it is still using the AMD Radeon HD 6970M GPU

I thought this should have been disabled by the "nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=%01%00%00%00" command?

Does this mean that the AMD GPU is working? But i moved I already moved all the AMD* kext

Does this iMac also has a integrated gpu like the macbooks discussed in this thread? I can't see it in the system report.

Hope somebody can provide some clarification. Thanks.

 

[Ausdauersportler]

Your GPU is dead, signs are apparent and well known, but there is a solution.

Try this:

2011 iMac Graphics Card Upgrade

iMac 2009 to 2011 MXM3 graphics card upgrade (Lastest update 10/13/2023 - this is the official documentation page - you found it finally!) This is the single and only documentation post. During the last years we constantly updated this post to reflect the lastet development of vBIOS and OCLP...

forums.macrumors.com

Did you ever try to use the search button on top of the page

 

[lastdrop]

Hey @Ausdauersportler, thanks for the reply. Guess I'm still in denial but I do found a a lot of thread about the GPU issue but haven't explored the upgrade/replacement option. Thought I can use the integrated graphics like with the macbooks.

I'll go over that thread. Thanks

 

[Ausdauersportler]

Hey @Ausdauersportler, thanks for the reply. Guess I'm still in denial but I do found a a lot of thread about the GPU issue but haven't explored the upgrade/replacement option. Thought I can use the integrated graphics like with the macbooks.

I'll go over that thread. Thanks

You are welcome, it will not be an easy task, but the result is worth it!!

 

[lastdrop]

Ok, after around 20 pages of front/back reading here are some notes that I took (i'll just make this thread as my journal):

• Seem like K2100 is one of the most recommended GPU (Aliexpress link)
• Need a CH341A clip programmer to flash the GPU (Aliexpress link)
• ifixit guide to replace the GPU (ifixit)
• i think this one is more applicable to me

Need to explore more about the OpenCore (what/why/how it is used)

 

[Ausdauersportler]

Ok, after around 20 pages of front/back reading here are some notes that I took (i'll just make this thread as my journal):

• Seem like K2100 is one of the most recommended GPU (Aliexpress link)
• Need a CH341A clip programmer to flash the GPU (Aliexpress link)
• ifixit guide to replace the GPU (ifixit)
• i think this one is more applicable to me

Need to explore more about the OpenCore (what/why/how it is used)

I got the CH341A on Amazon here in Germany for less than 15 Euro. No need to wait for China. At least in the US you will find cheaper cards than in China, here in Europe around 90 (best offer this week) and 149 on eBay.

OpenCore is just an image copied to an SD card to boot from. This can by tackled after the flashing and hardware installation.

If you are a unix guy you may flash using a Linux stick and boot it, but strongly recommend using the CH341A. You will have (hopefully) a working card after installing it and no "dark screen" experiences...

 

[macpro2000]

Time to throw it away and get a new one when the new ones arrive. a 27" 2011 isn't worth spending over $100 on anymore. Sorry.

 

[Ausdauersportler]

Time to throw it away and get a new one when the new ones arrive. a 27" 2011 isn't worth spending over $100 on anymore. Sorry.

This depends completely on what you are usually expecting from your environment. In terms of used power/work done a fresh system cannot be beaten, but for casual users this upgrade let the system probably exist for 5 more years. Since our world has limited resources - some people think different here - there is also another gain of making industrial products work a long, long time.

 

[lastdrop]

Time to throw it away and get a new one when the new ones arrive. a 27" 2011 isn't worth spending over $100 on anymore. Sorry.

Prior to this issue, I can still post-process and manage high-res RAW photos, edit videos, mix and process midi/audio, run docker containers / single cluster kubernetes, run VMs on virtualbox, run and test apps on IOS/Android simulator, etc - with ease.

~ $3k vs ~$300 on reviving a machine that can still decently do the workload above? I'd say it's still worth it.
[automerge]1587822738[/automerge]

I got the CH341A on Amazon here in Germany for less than 15 Euro. No need to wait for China. At least in the US you will find cheaper cards than in China, here in Europe around 90 (best offer this week) and 149 on eBay.

OpenCore is just an image copied to an SD card to boot from. This can by tackled after the flashing and hardware installation.

If you are a unix guy you may flash using a Linux stick and boot it, but strongly recommend using the CH341A. You will have (hopefully) a working card after installing it and no "dark screen" experiences...

I'll try to source the CH341A locally (Australia) but most likely I'll have to purchase the GPU from Aliexpress since I can't find it here.

Yeah I have a raspberry pi3 here that I can use so that should be covered.

By the way, would you be able to confirm if I don't need to pull out the logic board to remove the GPU in this model? Thanks

(This was before I replaced the SATA drive with SDD)

 

[macpro2000]

I’m just saying the fix is more than what the iMac is worth.

 

[Ausdauersportler]

You have to get the complete logic board out. Please pull the memory modules out, first. Since there is no cable plug in double use you can disassemble and reassemble without marking each and every cable. Just take a picture before.

www.ifixit.com has some nice guides with pictures step by step.

You could have two 2,5' SATA SSD because the board has two port, one is unused. The most complicated phase is when pulling the board and still having the SATA and power cables connected on the back side.

Aliexpress will give you the card of choice. Just make sure to be able to return in case of a DOA. Read this thread ....and ask there. This is the right place to continue...

 

[rc3105]

I’m just saying the fix is more than what the iMac is worth.

$11 for a K1100m plus a dollop of heat sink grease is a pretty cheap repair.

Sure you can get busted iMacs for $50 but that doesn't mean they're all worthless. A working 27" will still bring $400+ on craigslist here. (no that's not speculation, I've flipped a few dozen during the Covid shutdown)

And this in Austin Tx where much faster Dell are left on the curb for bulk pickup...

 

[lastdrop]

You have to get the complete logic board out. Please pull the memory modules out, first. Since there is no cable plug in double use you can disassemble and reassemble without marking each and every cable. Just take a picture before.

www.ifixit.com has some nice guides with pictures step by step.

You could have two 2,5' SATA SSD because the board has two port, one is unused. The most complicated phase is when pulling the board and still having the SATA and power cables connected on the back side.

Aliexpress will give you the card of choice. Just make sure to be able to return in case of a DOA. Read this thread ....and ask there. This is the right place to continue...

Ok cool. I've ordered the GPU from aliexpress - now the waiting begins (~20 days). Cheer mate.

 

[PozziePAW]

My GPU died like yours and I looked around for a solution. I came across this video and rather than an expensive paperweight I decided to give it a go and it worked (to my disbelief and amazement). I know it looks scary but give it a go, you can send the new one back?!? Worth a try, worked like a charm for me and still going strong! Throw in an SSD while your at it Made my machine run like new!!!

 

[rc3105]

Putting a defective part back in is just dumb.

Drop a k1100m or k2100m in and the machine runs quite a bit better than new. Faster, cooler, able to run Catalina...

 

[PozziePAW]

Would swapping the card natively allow Catalina update?

Mac (27-inch, Mid 2011), High Sierra 10.13.6
3.4 GHz Intel Core i7
20 GB 1333 MHz DDR3
SSD
AMD Radeon HD 6970M 1024 MB
[automerge]1588224003[/automerge]

Ok cool. I've ordered the GPU from aliexpress - now the waiting begins (~20 days). Cheer mate.

Could you provide details of what you ordered pls.

 

[lastdrop]

Would swapping the card natively allow Catalina update?

Mac (27-inch, Mid 2011), High Sierra 10.13.6
3.4 GHz Intel Core i7
20 GB 1333 MHz DDR3
SSD
AMD Radeon HD 6970M 1024 MB
[automerge]1588224003[/automerge]

Could you provide details of what you ordered pls.

Hi. Thanks for sharing your experience. I ordered this one: https://www.aliexpress.com/item/4000030895802.html

Yeah I'm hesitant to do the baking route since it is known to break down again. If I have to tear down my imac, I might as well replace the GPU with a better one so I can upgrade OSX to newer version

 

[PozziePAW]

Thanks Lastdrop, updating the os really appeals to me and I may well put one of those in. My Mac is still pretty fast as I went for the i7 and have 20Gb Ram, with the new SSD the only real issue is the USB2.0. That said I don't really need speed from hard drives anymore just storage but the real killer now is the old OS. If the new GPU (which I didn't realise one can "upgrade" on a Mac) works and allows "native" Catalina (mine stopped allowing OS updates at Mojave) i'm in. It's the only real reason why I would consider dropping 4K on a new machine.

I would really appreciate an update on you findings. Hope the fix gos well.

Thanks for the details on the new GPU, was that new or reconditioned?

 

[rc3105]

There are several video cards that support Catalina. You'll need dosdudes Catalina patcher and the Open Core bootmanager.

There's another thread covering usb3 on 2009-2011 iMacs, the card is only about $30.

 

[PozziePAW]

There are several video cards that support Catalina. You'll need dosdudes Catalina patcher and the Open Core bootmanager.

There's another thread covering usb3 on 2009-2011 iMacs, the card is only about $30.

Ok, so I like the look of the AMD Radeon WX4170 thought while I’m doing this may as well go for a more “modern card” with higher specs (than the NVIDIA Quadro K2100M) . I am troubled by the process of flashing the bios using the clip thingy (yes you’ve guessed it I’m not a computer wizz but have replaced the hard drive and did the gpu bake trick as explained previously) this looks very complicated to me and I can’t find a video which explains it “to a novice” without spewing technical jargon that I don’t understand. So could you please advise if 1. The AMD Radeon WX4170 is suitable (would not cause overheating issues etc). 2. Do I need to flash the bios. 3. Are there other issues with this card as seems to be pointed at like brightness control etc. I know I’m asking a lot but help would be appreciated!

 

[rc3105]

Not a clue. I'm sticking with the K1100m and K2100m because they're fast enough, run cool and everything works.

If I needed a mac with higher performance I'd build a cheap 16 core hackintosh and keep a lovely 27" iMac for target display mode ;-)

 

[PozziePAW]

Not a clue. I'm sticking with the K1100m and K2100m because they're fast enough, run cool and everything works.

If I needed a mac with higher performance I'd build a cheap 16 core hackintosh and keep a lovely 27" iMac for target display mode ;-)

Did you flash the chip?

 

[rc3105]

Installed K1100m with heatsink grease and silicon pads (instead of k5) for the ram chips.

Booted Xandrons linux image from sd, ssh'd in and ran the nvflash_linux util.

2011 iMac Graphics Card Upgrade

so guys, I have a little gift for you to give back after such an incredible thread :D hope you like it, the headaches to get it running were immens for me as a newb. I couldn't stand it to use fckin windows to flash the cards and so I prepared this ~350mb drive I created a Linux Live USB...

forums.macrumors.com

Rebooted into MacOS & copied the OpenCore files into my EFI partition.

Reinstalled the lcd & closed up the iMac.

 

[PozziePAW]

Thanks I may give it a go. Just have to convince myself as my system works fine after cooking the gpu about 2 years ago now 😬

 

[HelpMePls]

Hi. Thanks for sharing your experience. I ordered this one: https://www.aliexpress.com/item/4000030895802.html

Yeah I'm hesitant to do the baking route since it is known to break down again. If I have to tear down my imac, I might as well replace the GPU with a better one so I can upgrade OSX to newer version

THANK YOU LAST DROP! What’s the update on replacing the GPU?

I just made a post about it enquiring specifically about the brightness.

Would you know if the K2100m / K1100m affects it at all?

thank you.