Are you sure its the card and not the cable, when you replaced the card and moved the cable around, a short in the cable could be temporaily unshorted.
Also there was an issue with Nvidia drivers and varoius video cards but mostly with 6600, with screens set to high resolution and games set to high settings, people reported white tic tac toe/white rectangle pattern.
Heres a few pics when I had the issue with my BFG 6600 gt.
Also there was an issue with Nvidia drivers and varoius video cards but mostly with 6600, with screens set to high resolution and games set to high settings, people reported white tic tac toe/white rectangle pattern.
Heres a few pics when I had the issue with my BFG 6600 gt.
