pc freeze after gaming

Whenever I close a game like Subnautica or Halo Infinite or really anything that gets my pc running hot, all of my windows apps like discord and chrome will freeze and give me "not responding" for about 5 to 10 seconds. No weird sounds, but obviously voices on discord and videos cut off because...

I've only really experienced it on Valorant, being its the game I play most, but it happened once on Destiny 2. Completely random, whether its alt tabbing, closing, or starting up Valorant, my PC monitor will freeze, mouse still works, audio on discord still works, but I cant click anything, and...

As I mentioned, the screen freezes when I start playing and the core clock is on factory settings, but the problem is solved when I lower the core clock to -200 MHz . I don't know why I have to lower the core clock from its base speed. I have been playing on the same factory settings in the past...

With weird i mean white and blue or diferrent colored squares all over it, this usually happens when i play 3d games, if the pc doesn't crash and i am able to close the game, for some reason, if i play it for a while and then decide to close the game and open any other program or try to turn off...