Nothing works, every game freezes after a few minutes

Sorry if this has been answered. Im a noob and having been trying for 2-3 days to get any game to work. even the known good ones on the compatibility list. They all seem to work at first. They boot and play at a good FPS, for about 2 to 10 minutes. After that the game freezes solid and I have to use task manager to force close. Ive tried stock settings. Ive tried playing and messing around with the settings and it makes zero difference what I do. 100% same problem, every game, every possible combination of settings. Not sure what im doing wrong here. Thanks in advance