Question PC either freezes within 5 mins of playing games OR plays fine

[-. Dave .-]

My PC has 2 strange issues:

1) About 50% of the time if I start a game the PC freezes within 5 minutes (the image freezes and speakers make a buzzing sound) forcing me to restart. But if I make it past the first 5 minutes, then it hardly ever crashes

e.g. (Civ 6, Borderlands 3, Assassins Creed Odyssey and Assassins Creed Origins)

2) When I shut down the PC, it often immediately restarts

Spec:

Processor: i7-4770K 3.50Ghz
Ram: 16gb
Graphics: GTX 1060 6GB

I got the PC in 2013 and added the graphics card more recently so maybe there's a weak link in an older element? Or maybe it's the graphics card? Issues with games crashing did seem to start after I got the card. At first I thought the issues were with the individual games, all of which do seem to crash for people often, but the pattern of how they crash is identical for me across all of them. I'm not certain when the restarting issue began as for a while I jut thought I must be accidentally choosing restart.

The graphics card driver is up to date and I don't think it's overheating.

Any advice would be much appreciated.

 

[rgd1101]

brand and model of the psu?

 

[-. Dave .-]

Be Quiet system power 7 700W (BQ SU7 700W)