Screen goes black/greyish sometimes while gaming.

[asd___]

Hey guys. I have this problem that I never had berore. Often when im playing something my screen just goes black but i can hear game sounds etc. Even when i reinstalled drivers for gpu it kept doing it and still does. (I even made my gpu stock speed.) Sorry for my bad english.

 

[InfernoVortex]

What's the name of your graphics card and how long do you have it?