Black and grey screens, general freezes every time on 7870

LordPlanketh

Honorable
May 11, 2013
49
0
10,530
Every time I launch a game, I can play it for 10 minutes before my computer crashes into a grey screen with shaded lines, a black screen, or just doesn't work. My temperatures are actually below average, and so I shouldn't be getting any problems. But I do. My rig:
-AMD FX 8120
-Asus M5A78L-M/USB3
-8GB Corsair RAM @1600mhz (not sure exactly what the model is)
-750w PSU
-1TB Hitachi 7200rpm Hard Drive
- VTX3D Radeon HD 7870 black edition (Tahiti LE)
-CIT vantage case
Please help! :)