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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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A1312 not powering on because of GPU? LED 1 present

Past few weeks, I posted a few questions on this website regarding my iMac A1312 not turning on. LED 1 kept lit up so I know there is power coming in.

No chime, no fans, no nothing when I pressed power button.

I changed Power supply, the DC cable, power cord, logic board AND the power button.

NONE of it was the reason that my iMac does not turn on.

In my last resort, I tried boot it without GPU then BAM! I got LED light 2.

When I try to boot up again with GPU slotted in, it went back to LED 1 light only and nothing works. I know I will get a new GPU but my question is, in my countless research of LED 1 and no LED 2, 3, 4 symptom, none of the article mentions faulty GPU.

FYI, I tried the “baking GPU” just in case. Nope, it did not work. I know I will get a new or used GPU now. :(

Is it something new? or am I going down to another rabbit hole. I spent SO much money on this iMac already. Any help would be appreciated.

Answer this question I have this problem too

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That 2011 27” had an Apple replacement program (now expired). This is a well known issue. It usually starts with screen artifacts or blue lines on it. I have two in the shop now for GPU replacements. I use the 2GB GPU cards. Only problem is that they are currently only available from China and take a couple of weeks to get. Cost is right at $200.00

Do a search for, NEW 661-5969 Video Card AMD HD 6970M 2GB For iMac 27" Mid 2011 A1312

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thank you so much for following up. If I want to buy used one from eBay is it viable? I will be using this computer for youtube + web browsing only. NO GAMES. So I'm thinking 512MB or even 256MB GPU would suffice. Not planning to spend $200+ when I'm so much into it financially. I hope some where in $50 range for new/used GPU. Will other GPU (from A1311 or something) work on this?


A used one may put you right back into the same boat. Search for new:

AMD Radeon HD 6770 (512 MB of VRAM) - 661-5967

AMD Radeon HD 6770 (1 GB of VRAM) - 661-5968


sure I'll look into that.

One last question, will HD 6750 work for iMac 27"? They use it on iMac 21" but wondering if it'd work for 27" as well.


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Shawn Kay will be eternally grateful.
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