Computer crashes everytime I play a game on the PC

Every time I play a game like Red Orchestra 2 etc. on my computer, it crashes. The screen turns black and it locks up completely. Pressing ctrl+alt+del does not work so I have to restart. My NVIDIA driver has been updated but still it didn't work. I noticed that when it crashes, the fan spins in full blast. Could someone tell me what might be the problem? Is my graphics card broken?
