So I've been having this issue with my PC since I got it. When I play any game randomly my screen goes black and comes back with my FPS going to around 30 when it was at 300.
I have a GTX 670 2 GB, 800 wat power supply, 2 TB hard drive, 16 GB ram, and I'm running games at 1980 x 1080. I play LoL, diablo 3, and Bf3 and the problem occurs with all of them.
I updated and I still have the issue. Just now my whole computer froze and sound looped I had to power off manually. I know it's not my hard-drive because I just got a replacement for a different problem. Also it seems like my monitor looses the signal of my computer when I have the FPS drop.