I play about 5-10 minutes and then... everything goes black and the audio stucks like a scratched CD... only then my PC reboots.
Didn't hear about nobody having this problem so far...
What shall I do?

Call me... Bluescreenborne.
EDIT: Using a poor ol' Nvidia GT 220.
If someone thinks it's better buying a new VGA, tell me one. I'll buy it tomorrow ??
But if there's anything I can do to play with this GT 220 for now... I'll be happy.
'bout the system:
I5 with 2.4GHZ (overclocked to 3.0 if I may)
8GB Ram DDR3 1333MHZ.
(Yeah, I work with 3D. Didn't care about buying VGA since 3d softwares does not use massively VGAs. wel.. whatever..)
