PC shuts down when loading usual games

My computer started shutting down completely (all components shut down & no monitor signal) everytime I try to load a game. They're all games I've run fine before with decent stats. It originally started only when loading FarCry3. It happened another time before with War Thunder, only when loading into the lobby though. Now it happens with every game.

The PC temps seem fine, all around 40-50c, I've updated the GPU drivers, Java, and other programs.

Plugs and connections seem fine. Computer is only slightly dusty, I cleaned it a little more as well.

One weird quirk is I have to flip the PSU toggle switch and wait for what sounds like a capacitor to power out before I can toggle the switch again and restart it. Any opinions? I think I might need to replace my PSU but that's mostly just a guess. ¯\\\_(ツ)\_/¯