Working GPU not recognized by two different motherboards in primary PCI-e slots

Claisen42

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Jun 29, 2015
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My current hardware is a Radeon HD 6950, Intel i5 2500k and two different motherboards. Original motherboard is an ASRock P67 Extreme4 Gen3 and the second board is Gigabyte B75M-D3H. I also have a corsair H80 cpu cooler and x2 4GB G.Skill Sniper DDR3 1600. Two 1 TB WD Black and a ~160GB SSD Corsair Force GT.
A few days ago I noticed by CPU was running hot and when I opened the case, the two radiator fans were performing poorly. I reseated the CPU and redid the thermal paste. I also used compressed air and vacuum to clear out dust around my case.
When I went to restart the computer, (using the ASRock motherboard) nothing would be displayed on the screen, the motherboard debugger indicated an error d6 which indicates no Output Console Found and beeped 5 times. I attempted to debug the issue by doing the following steps:
Reseating the the GPU. Reset CMOS. Reseat the GPU again. Proceeded to strip the entire setup and set up the bare essentials on my table. Re seated the CPU and redid the thermal. Carefully inspected the pins on the motherboard and found no obvious bent pins. Cleaned the golden contacts on the GPU and reseated. Moved the GPU from PCI-e slot 2 to slot 4 with no changes. In PCI-e slot 6 (x4) I would get graphic displays and the computer would seemingly function normally. I did a reinstall of windows without issue.
I had a friend come over and tested my GPU in his machine and it functioned without issue but still wasn't able to get a GPU working in PCI-e slots 2 or 4. My case won't allow a GPU in PCI-e slot 6 plus at (x4) my graphic card would be severely limited in its performance.
Since the CPU seemed to be functioning (because being able to reinstall windows) and the GPU was working I figured I must have damaged the motherboard and went ahead and purchased Gigabyte B75M-D3H. I set up everything again with the new motherboard, but still the GPU in first PCI-e is not recognized. If I plugged the display cable directly into the motherboard utilizing the integrated graphics in the CPU I then get a normal start and visual display.
My question is: since I’m having the same issue on two different motherboards what additional troubleshooting can I do? Is the PCIe x16 slot controlled by the CPU which is why the motherboard isn’t recognizing it? I’m not sure what to do at this point though I’d rather not just buy a whole new system. Thanks for any help.
 

Claisen42

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Jun 29, 2015
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I might be able to check with another 2500K. I just wanted to see if there were any other things to check since CPU's are rarely the component that fails and every other part of the CPU seems to be function perfectly. Is there another way to test if part of the CPU is damaged?
 

kraelic

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Feb 12, 2006
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With the GPU fine in the friend's PC and the two motherboards not working, it leaves the CPU. The graphics in the 2500k talks directly to the B75 outputs on the mainboard, not over the PCI Express as it does with the x16 slots. The x4 comes of the south bridge. Other than swapping in another CPU and seeing if the original board and GPU work, RMA to intel maybe?
 

Claisen42

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Jun 29, 2015
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Thanks kraelic for the insights.

I'll try the CPU swap tomorrow. The CPU is ~3.5 years old so past the warranty period. I think its about time for me to get a replacement though I am a little sad that I wasn't able to get more life out of it. Seems strange that only the portion of the CPU that was damaged controls the PCI-e as I have been using the integrated HD 3000 without any issue.