[BigE4u]

Im willing to help here... may i suggest you first check the fan on the heatsink on the card to make sure its still spinning fine or it might be slowy dying if its not excesively dirty, then clean it. What looks like is happening is because the video card GPU(core) is overheating. If the fan is good, then i would suggest changeing out the white thermal grease the manufacture puts in and replace it with some arctic silver5 between the hsf and core. Remember to put alittle more in the center of the gpu because it has a concave(sunk in) like surface. If all the above didn't help, maybe its time to retire that card and get a new one or get a replacement HSF for it from thermaltake and try that... good luck.