Do the fans and temperatures eventually drop without going back to a game or do they continue to stay high?
Open either Task Manager or Resource Monitor. Slide the window to one side and leave the window open
Watch system performance for a while and to nothing. Then game as usual but leave the window open.
Observe what is using the GPU and to what extent. But do pay attention to other system resources as well.
Then tab out of the game and try to identify what changes. Then tab in again as you have been doing. Hopefully you will be able to identify some issue that corresponds with the fans and temperature behavior.
Also -PSU: make, model, wattage, age, condition?