Hi folks, I've an iMac 27" 2011 with the infamous GPU failure. At the same time, I've a known working AMD 5750 pulled from an iMac 27" 2010. I've tried swapping the GPU, which resulted in the machine chiming when boot but a black screen. The third and forth diagnostic LED on the logic board did not lit up, which indicated that the GPU is not communicating with the logic board. I was wondering if there is anyone who has done similar "downgrading" of GPU with success.
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iMac 27" 2011 GPU downgrade.
- Thread starter MysticIce
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I have swapped 2009-2011 GPU’s without problems.
I would expect a badly seated card.
Did you check that the x-clamp fits directly, and that the cooler does not interfere with the caps on the top front side?
This is the solution. Read the first page to see which card suits best.
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
After swapping these cards 12-15 times, I can add the following to list of notes to your situation;
Check all caps on the mainboard near or below the MXM socket.
A casually inserted card might have torn off a cap. You might have to use a magnifier or microscope.
It will require great soldering skills to revert the damage, but I suggest doing so, compared to just trashing the mainboard as these are expensive even used. I have successfully repaired one board myself, and had 2 other repair by a more experienced amateur.
I’m adding a picture but do note that ANY smd component slightly off orientation might be damaged.
You can normally refit the same component unless you tore off soldering legs.
You will have to completely remove the logic board to examine both sides.
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I think this is exactly what I've just done to my 2010/27... Have the same issue - screen powers on but stays black - I must have knocked something off in inserting the card...
Possibly.
Pull out the main board completely. Examine it under a microscope or magnifier (I use iPhone 11 Pro build-in magnifier app), especially above and below the XMX slot, front and back.
You should be able to recognize any component missing or (partly) knocked off.
If you post a picture, I might be able to examine the diagram and tell you what you knocked off.
I personally saved 3 main boards this way.
Thank you, first I want to check if it will output to an external display to rule out any damage to the LDVS connector/cable (I am waiting for a mDP adapter in the post). The card is definitely inserted correctly, I have reset twice now and it is snugly in there.
However I am unable to see the diagnostic leds (see here for more details of my issue https://forums.macrumors.com/threads/help-me-work-out-what-ive-done-to-my-imac.2244904/) - I must be looking through the wrong place, but the diagnostic manual says you have to look through the lower vents next to the RAM, but it is very difficult to see and I can't really work out how many lights there are there! At least 2 though, possibly 3?
I don't have the skills to fix the logic board, and it is probable not economical to repair. And to be honest I can probably buy a 2010/2011 iMac with a broken GPU for pretty cheap, and transfer the insides (SSD, RAM, GPU) to the new iMac, sell the bits of my old one (LCD, PSU, CPU, etc) and it might not cost me very much in net terms.
Once I've ruled out LDVS issues, I will take out the iMac apart and send you a picture of the board - I don't have a magnifying glass or an iPhone 11 but I will try my best...
Theres a factory installed black piece of tape covering the 4 diag leds, did you already remove this? You may need to take the main board out to remove it.
In your case I would definitely remove the main board. Both to remove the black piece of tape (if present) but also to inspect the area around the MXM slot.
The incidents where I damaged the main board was exactly the 2009/2010 27”s, where its enticing to pull out the GPU without removing main board.
I suggest thats why they changed the basic design on the 2011 model.
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Thank you very much!! I wish this was clearer in the diagnostic manual. I managed to remove the black tape by reaching into with some tweezers.
This is mysterious - all 4 LEDS light up, but the screen remains black...
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And you already sucessfully reset SMC and PRAM, correct?
Do you reset PRAM by holding the keys untill the sound is heard THREE times?
One further possibility could be to remove the PRAM battery (located on the back side of the main board) for anywhere between 10 minutes and 24 hours.
But to be honest I would look further into the main board components around the MXM connector as specified.
Theres no way around removing the main board in my opinion.
It should take no more than 15-30 minutes in total if done correctly.