Temps of the GPU are at most at 70-72°C, the CPU is at around 55-75°C depending on use while gaming.
RAM runs in Dual-Channel yes
Reinstalling windows... yeah, that would be my last resort as well, but I want to avoid that at all costs at the moment, because I hate doing that and that might not even be the solution to that
I might do that sooner or later since I'm having some other strange issues with internal windows programs like the game bar and such things.