Check if the 2 6pin cables are tightly connected to the gpu adapter first.
If no driver works, then it could indicate a hardware failure.
If the card does not overheat from accumulated dust and dirt, the fan works good, and the tim does not actually need to be replaced, then you may also have issues with the vrm or vram chips of the card.
What gpu were you using before ?
the 2 6pins should be tightly, yes.
well, the default windows vga-driver-something work without artifacts and crashes. its after i install the AMD CCC + driver the failure starts. thats why i think its the driver doing it.
and the card didnt overheat or anything before i got it. not sure what this "tim" is in this case.
before (or now, since the 7950 doesn't work) i use a xfx hd 5770 without any problems.