Then it should be a software problem since the system is not really freezing, just your window manager probably. Temperatures are good. I am no expert for the p

Then it should be a software problem since the system is not really freezing, just your window manager probably. Temperatures are good. I am no expert for the possible causes here, my uneducated guess would be a driver issue or some incompatibility with your hardware. Reinstalling is a lot of work but might help. If you don't care for LTS versions, perhaps try a newer one. But that is all based on guesses, maybe ask in a forum specifically for Ubuntu and tell them about the specific hardware you are using. Perhaps someone has similar experiences.