Model A1311 / Mid 2011 / 2.5 & 2.7 GHz Core i5 or 2.8 GHz Core i7 Processor

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What GPU I can put for test?

Guys need help,

Have a problem with iMac, I guess I have dead GPU (I have another thread about this, it's not a question). My replacement part cost quite a lot, and not easy to find (HD6750M), what if I'll find any working GPU MXM size that will fit my iMac (some dirt cheap from eBay). Can I put it in and try to see if the system will run, at least start up?

I know that it might not work properly on Mac systems, but at least if I'll get a boot screen I can be sure that my GPU dead and needs to be repaired/replaced, because if I'll spend $200-$300 on it and it turns that it's not a problem it will be sucks...

Answered! View the answer I have this problem too

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So your focus here is how to diagnostically test your system to find out if the GPU is bad or not - Correct?

I would start by trying to connect an external display to see if that works or shine a flashlight into the display to see if you can see the faint image of your desktop & icon's (you'll need to shine the flashlight at a sharp angle and right on the glass)

Then if that didn't offer any clues are you are aware of the diagnostic LED's on the logic board? Diagnostic LED's

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I've tried external monitor - same thing, nothing. And I have 2 LED lights from 4, so I assume that is GPU. And you know if it will be a PC desktop, I can took any GPU and put it in to see if that will be solution, so the question, can I do the same with my iMac, with "any" GPU that will fit (MXM III)?


Sadly, you can't use just any MXM graphics card. Apple has custom firmware on the ones they use. You also need to use one that fits the tight spaces within an iMac. See Mayer's answer for the P/N's for the two cards Apple offered in this series.


Agree, thanks for the answer!


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Most Helpful Answer

To confirm a bad GPU, hook it up to an external monitor and see if you get a picture. Most of these bad GPU just need reflowing with a hot air work station. The reason they are so high is supply and demand. There were a lot of failures. There are several services offered on eBay that will either do a reflow or replace the chip. I have used BrickFence a couple of times before I got my hot air station.

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Thanks for recommendation, unfortunately this BrickFence is the one of the most expensive (compare to others on eBay). Anyway, how about my initial question, can I put "any" GPU for test? I've tried external monitor, still nothing, and two LED lights (from four) on the motherboard...


As far as getting a repair, check the warranties, reputation and service times. I have found in life, that except for this site and the good hearted volunteers who do this for free, you get what you pay for.

These are the only two cards that I am aware of that will work in this model:

Replacement, 21.5" iMac Intel Core (Mid 2011) AMD Radeon HD 6750M 512MB Video Card 661-5944

Replacement, 21.5" iMac (Mid 2011) AMD Radeon HD 6770M 512MB Video Card 661-5945


Thanks, appreciate that!


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Konstantin Ogurchenkov will be eternally grateful.
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