I think it's the graphics card...

[Rostum]

have you installed any applications to tell you what temperature your cpu is at?

Ah, no. I've just tested the GPU temperature... Any suggestions for a program that will do this?

If his computer was overheating, wouldn't there be artifacts all over his screen? My desktop overheated once and it damaged the video card, now it leaves artifacts everywhere no matter what temperature it is.

Not necessarily. My graphics card isn't damaged.