So I've been having this problem going on for like a month already and didn't really care before but now it's getting annoying. Whenever I play games like DotA 2, LoL, CoD on my PC, after a few minutes the screen suddenly goes black and says 'No Signal'. I looked around the net for solutions and most say it's most likely a GPU problem. So I thought it was overheating, I checked the temp with GPU-Z and it was only around 50-60C. I also just cleaned my fans and checked if the GPU fan was working but still nothing changed. Currently, I'm running the CPU without the GPU and I'm gonna test if it'll shut down on my games (I don't think this will work though since I probably wont even be able to run the games). If nothing happens, I'll probably format the PC. But before that, what else do you think I should do? What's causing this? I don't want to bring it to the shop unless that's the only choice I have.
Specs:
CPU : i3-2120 3.30GHz
RAM : 8GB
GPU : GTX 560 (non - Ti)
PSU : 600W
Oh, another thing. My OS is expired. However, I doubt that's what's causing this.