Xigna.
Would this make the screen go blank on HIGH powered games only?
I.e. Games with a lot of colour, graphics, action etc.
Might be your graphics card to be totally honest with you, or RAM..
Download a RAM checker from Microsoft.
http://oca.microsoft.com/en/windiag.asp
Also run dxdiag to check out your VGA card.
I feel its your card locking up.
Have it swap tested if possible.