Weird dropout and other behaviors just started happening

[Starship Krupa]

I wuz gonna say that if your CPU is getting hot enough to throttle, whatever the CPU load, you need to either repair or replace your CPU cooling system. Looks like you figured that out.

My favorite tool for monitoring temperatures, fan speeds, CPU core clocks, etc. is HWinfo. It has 3 different modes, one of which is "sensors only." I keep this running all the time on my main system, as it keeps track of minimums and maximums of whatever it's monitoring over time. The other two modes are system configuration reports, one of which is the most detailed of any such report I know and can tell such things as what devices are plugged into the system's various USB controllers, what date the RAM was manufactured, and so on.

Keeping HWinfo's sensors running during your present troubles would reveal your current, average, minimum, and maximum CPU speeds and temperatures. It might be interesting and valuable to check it before and after you replace the cooling system.