PC freezes and goes to black or random color screen after an hour of playing games

[theatrisss]

My PC crashes after about an hour of playing any game ( The Forest, Ghost Recon Wildlands) my GPU, CPU and motherboard are new ( GPU: Evga Gtx 1070, CPU: Ryzen 5 1600, MB: MSI B350 PC MATE, my PSU is quite old and I'm not sure if that could be the isssue because my old pc build had sometimes the same issue. When I first got all the new components I had no problem with it, it only started doing it recently

 

[Peter Martin]

check the psu with occt

 

[theatrisss]

check the psu with occt

How exactly ?