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Model A1312 / Mid 2011 / 2.7 & 3.1 GHz Core i5 or 3.4 GHz Core i7 Processor, ID iMac12,2

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AMD Radeon HD 6770M on iMac can be replaced by AMD radeon 6970

I am having problems with my GPU, I do not want to buy a new iMac if can be fixed and even better upgraded. I know I can try to find the same, except GPU, but I want to know if I can get more than 512MB on video, making opening my iMac worth it? BTW, mine is iMac 2.7ghz 27 inches with 512 video card.

Update (02/01/2020)

Hi Dan,

Thank you again, I do not know if I could attach the image well, I try answering but I do not know where it goes, so I edit my question adding this image and looks fin on my computer.

Block Image

That time that screen was like in the picture, the computer after few seconds reboot and start again. the next time was black screen and I have to shut down by pressing the start button for few seconds.

I am pretty sure I am able to turn on my computer again but i want to keep it alive until i found the proper solution or replacement.

Looks like I will need to get the tools to open my iMac and learn how to do it, anyway is not working, so is a good excuse to try to fix it. Its a shame because the screen is really good, those 27 inches are great for my eyes and for editing.

I know is an old computer and until last year I was very happy with it. so I hope you can see the photo and might be give you a clue what can I do.

Thank you so much.

Answered! View the answer I have this problem too

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Apple offered three GPU options for your system

  • AMD Radeon HD 6770 with 512MB - P/N 661-5967
  • AMD Radeon HD 6970 with 1GB - P/N 661-5968
  • AMD Radeon HD 6970 with 2GB - P/N 661-5969

Now the tricky part! All of these GPU boards are hard to find as many people pushed their systems hard or failed to maintain their systems cooling burning them out.

AMD & Apple didn’t help matters as both used lead free solder (relining on Tin instead). These early versions of lead free often failed from fracture and tin whiskers from the constant heat and cooling cycles this GPU board went through.

AMD has long since stopped making these boards and while you can find a few from other systems as Apple wasn’t the only one using them. The Apple boards have custom firmware which you would need to burn into the EEPROM so the board works properly.

If you want to salvage your systems GPU board you’ll need to take it out and clean the dust build up within the system. Cleaning off the old thermal paste and VRAM chips applying fresh paste and using thermal pads on the VRAM chips as the gapping paste Apple used was not as effective as the pads.

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Dan, thank you ver much for your quick help.

Yes, I might end up trying to use my GPU but is not working propertly. So I am affraid that cleaning and ppading process do not work.

so I can use any of these

AMD Radeon HD 6770 with 512MB - P/N 661-5967

AMD Radeon HD 6970 with 1GB - P/N 661-5968

AMD Radeon HD 6970 with 2GB - P/N 661-5969

on my old iMac? that would be great but as your advice of having to do that firmware (which I do not know how to do it) fix will be a not recomended solution for the $$$ I will end up spending. Just found a $300 used GPU so spending that money on an used part that might fail in few months would be painful.

Is Sad, because my computer looks like almost new. even the magic mouse is brand new because I never use it and the wireless keyboars is always been with silicon cover.

Well, I might need to think about my options and thank you again for your time and great answer.


@juanp001 - What is your system doing now? Post a picture so we can see what the display is doing: Adding images to an existing question

I would try the simplest fix first depending on what the display is showing you. In some cases I've re-soldered some components using a heat gun, others have used an oven to revive a dead board. While that might buy you some time a proper reflow is the better answer but that's not something I recommend a DIY'er.

The listing I gave you is directly from the 27" service manual. Apple offered all of these in different configurations when you originally bought your system.

See what you can find using the P/N's I offered you. Do stick with a real Apple board so you don't need to fuss with the firmware.


ok I will attach an image so you can have an idea of how it looks like.


@danj Hi Dan, Thank you for your advice.

GPU after sent to clean and re-thermal pasted works for only 12 hours then iMac shuts downs....

I mighttry to get tools so I will open, baking GPU and reinstalled to see if that works for some more time, otherwise I will try to get one of those used iMac gpu to replace it. do i need to change heatsink if I get a 6970 2GB to replace my 6770m 512MB? i saw some videos that wont need because those small chips are ok. What you suggest?



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I have a 27" mid 2011 iMac, vga board 5770m. It failed. Can any other apple vga card fit the same vga card cooler and in the same space with me just replacing the heat sink grease?

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Apple never offered the Radeon HD 5770 in the 2011 iMac's, Sounds like someone swapped it out before (older 2010 iMac used it). I listed in my answer the three boards which came in the 2011 27" iMac.

While some people have managed to fit in older lower TDP MXM boards (equal or less than 250 W) you'll get less performance as Apple was using the best MXM boards available at the time. You are still limited to what Apple used as the graphics drivers are baked into the OS so you don't have any options beyond that (while some boards will work in compatibility mode you won't get the better performance they offer). Then you have the physical limitations of the hardware and the cooler.

Bottomline: Just get the correct board if you can find one. And don't push your system with heavy graphics.


Hi, I would recomend if you will use different GPU get teh right heat sink for it. Do not buy a GPU from chinese sites.. they came bad and you loose the money as that happend to me using aliexpress, they sold me a cooked one and last only 3 days.


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Juan Pablo will be eternally grateful.
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