Computer unexpectedly rebooting

[QuestioningGuy]

This is weird. I can run everything in my system in full load and it won't reboot. Then I start playing anything. CS-GO and League of Legends works fine. All other games make computer to reboot. Event Viewer says this:

 

"The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly."

Is this PSUs fault?

System specs:

CPU: Q9400 3.25GHZ
MOBO: Asrock P5B-DE
GPU: Gigabyte OC 570 (not overclocked)
2GB RAM
PSU: Modecom 620w

 

P.S. PSU is about 7-8 years old

[CapricaBuccaneers]

Check to see if any of your components are overheating - if it's games it sounds like an CPU/gpu under load issue and the first thing I'd check is HWMonitor to see what your maximum temperatures are.

Edit: CS: GO and LoL aren't particularly demanding on graphics cards so that could be why you're not getting any problems playing those. It could very well be increased power draw on more demanding games (PSU problem) or your gpu heating up (graphics card problem).