[2021] PC restarts while playing the game.

By posting here you get the same people you did in your support tickets, just so you know!

I am still of the opinion you have a hardware issue with your machine. Have you had that checked out?  

I agree it is not temps, and unlikely to be drivers by this point.

IMO a better approach would be to take it to a hardware shop and have it looked into, especially if you can demonstrate the problem to them.