I was running two GeForce 8800GTs in SLI configuration when they suddenly stopped working. The screen resolution was stuck at 640x480 and 16 (64?) colors and the display manager would only list them as generic, though the device manager had them listed correctly. Testing them separately, I found one put out a signal as related above, while the other had an even worse (wavy, fuzzy) problem.
I have seen people revive video cards, but I took this as an opportunity for an upgrade.
If anyone out there has the skill to either fix defective cards or reappropriate the parts, he is welcome to these for the cost of shipping. Post your interest here.
Remember, you might receive two totally dead cards, so I suggest you only claim them if you can use the hardware. The SLI bridge is not included.