Monitor blacks out with a No Signal message requiring a hard reset

[morristhehorris]

When I am gaming, after a while (time period changes) my screen suddenly blacks out and gives me the No Signal message, I can still hear some sound in my headphones, but it appears to be looping (hard to tell depending on if I have the music off). There is no BSOD or anything, just an unresponsive computer, screen and pretty much everything. Sometimes, instead of black-screening, it just freezes on the current image with the same problem. I have no idea how to fix this, there are so many things that could cause it, I'm pretty sure it is a Graphics Card issue though.
It originally only happened with Kerbal Space Program (apparently very intensive) and I addressed it over there but no specific help but then it happened a few days ago with Just Cause 2.

My dxdiag specs:
http://pastebin.com/7HC7kL2v

Any help would be appreciated as this kind of makes most games unplayable for more than a few minutes, feel free to ask specific question that could help solve this problem.

 

[Spaniard United]

What does your heat situation look like?
Have you tried uninstalling/cleaning out your drivers and reinstalling?