PC restarting when starting games

[Matthew V]

My computer usually runs normal. Lately though, it's been turning off and restarting. No error message appears.
It specifically happens [not every time] when starting up games, apparently when graphics are loading up. I can still do anything else such as browsing normally, with no sign of malware.
I'm confident it's either the GPU or the PSU, but I want more opinions and info before I spend that kind of money.
Tools and methods to diagnose both are welcome.

I got:
Card - GeForce GTX 770 2GB
Power - EVGA SuperNOVA 650W 80+ Gold

 

[Grobe]

Had a similar problem to an Acer laptop. Weeks of searching the web and try to figure what is malfunctioning has culminated to the GPU overheating. Still not completely sure that was actually the cause (because attempt to repair went bad).

Anyway, it is more likely a GPU problem than a PSU problem. I had some bad PSU experiences, and the symptoms I have experienced so far indicates stability problems rather than sudden shutdown problems - but haven't tried to overload one yet.

 

[Matthew V]

GPU issue is probable, but I doubt it's overheating. Starting a game doesn't always result in a restart, and games run normally when successful. I have temperature readings at normal - never going above 50C.

Whatever is going on indicates is a sudden spike or foul-up right at the game's start-up. So either the card or something interfering with the power.

Anyone got tools for analyzing PSUs?

 

[Grobe]

Analysing a PSU require reading of ripple voltage (spechial electronic equipment), which the mobo itself cannot provide.
And so due to your assumption of a bad PSU, it's probably cheaper to buy a new one - even if it turns out that the PSU is good.