PC is shutting down randomly during heavy gaming

[Wildside]

Hey guys. Recently, I have noticed that my brother has been playing GTA4 and for some reason my PC chooses to shut down on it's own. Now, idk if it is just this game and others or just this game itself but it happens for whatever reason. Doesn't happen in Battlefield 3 or Diablo 3 though, so it is odd. I also noticed that my computer does shut down whenever I try putting it to sleep lately. Like, it goes to sleep but when i try to turn it on, it acts like it was turned off and reboots into BIOS again. I will run Intel Burn Test sometime for stress testing for CPU. Any testing I can download and use for GPU testing?

 

[MindoverMaster]

Use Furmark to stress test your GPU.

What temperatures of the CPU and GPU are you getting while playing? Get HWMonitor. Let it run ion the background while you play, and then look at it a few minutes in..

Also watch the temps when you are stress testing.

 

[Wildside]

Ok thx.