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iMac Late 2009 replacement GPU
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P
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Apr 25, 2016, 04:28 AM
 
So my old Late 2009 iMac died, and everything points to it being the GPU. I haven't pulled it apart yet, and I will be getting an MBP instead, but just for my information: What GPUs will work, if I can find a replacement? The 4850 I have now, the 4670 that was the other option, the 5770 that was the one in the facelift 2010 model... anything else?
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
reader50
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Apr 25, 2016, 04:49 AM
 
According to MacTracker, all the following are the 27" A1312 model.

late 2009: Radeon HD 4670 (256 MB) or 4850 (512 MB)
mid 2010: Radeon HD 5670 (512 MB) or 5750 (1 GB)
mid 2011: Radeon HD 6770M (512 MB) or 6970M (1 or 2 GB)

I just diagnosed an early-2009 24" with overheating GPU. It would work fine for a few minutes (more if the system was idle). The problem appeared to be the heatsink rather than the GPU itself. It's a heat pipe heatsink, and the coolant can apparently leak from the heat pipes sometimes. Since it leaks as a gas, there is no residue or secondary damage.

Anyway, if these symptoms describe your system, you may be able to get a used heatsink off ebay for a fraction of the price of another GPU.
     
P  (op)
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Apr 25, 2016, 08:28 AM
 
Thanks, but I already eliminated heat, at least heat as the current continuing cause. The defect shows up as lines across the screen at boot, then shifting to a complete crash when booting. I reset the SMC, which sets the fans to ludicrous mode, and sent the machine to recovery mode to clone the internal drives. Fans running at full blast for hours did not make the lines go away.

The cloning done, I tried to reset the PRAM to see if i I could get it to boot, but that appears to have made the screen black with no return. It COULD be a faulty connection internally, which would be easy enough to diagnose if I start pulling it apart, but the most likely answer is that the soldering balls under the GPU or its memory have cracked. It is apparently a common problem, caused by moving to lead-free solder, and one that can be fixed by reflowing the solder on the graphics card. I have not yet decided if I am stupid enough to actually try doing that.
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
reader50
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Apr 26, 2016, 01:08 AM
 
Certainly sounds like solder cracks.

About alternative GPUs, MacVidCards just made a blog post of interest. They're getting set to hack PC MXM 3.0 cards into Mac cards, primarily for older iMacs. Both direct replacements, and upgrade GPUs.
     
P  (op)
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Apr 26, 2016, 04:09 AM
 
Very interesting. This iMac could still have a bit of life left in it as a secondary machine if I can fix this issue.
The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.
     
   
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