Just for giggles, and it's free, check out the mounting of the hsf on that GF4. The crud they use could have easily dried out by now, making heat an issue for your gpu.
And while it's out of the system, clean the contacts with an eraser..that saved a card of mine from the skip.
And while it's out of the system, clean the contacts with an eraser..that saved a card of mine from the skip.