Whenever I play any game, my PC freezes after a few minutes. So finally I took the video card out to find out what was wrong, and found this:
I also thought the heatsink and fan were a bit dirty (dirty enough to cause cooling problems?):
overall view of the card:
This is (was?) my...
the black square acts as a thermal compound to help transfer heat off the cpu better, so don't take it off
read the instructions that came with your cpu if you want a better explanation about it