Yeah, grats you solved it
Maybe the power supply is not strong enough or not anymore.
I think the switching power supply decreases it`s performance, rather than the CPU.
The more you clock the CPU the more voltage it is needing to work properly.
So maybe also your mainboard can`t provide the volate or current the CPU is needing.
You can try to set the voltage manually ...
but be careful you can destroy your CPU
When the mainboard increases the clocks automaticly, it usually also increases it for other parts (RAM, ...)
So maybe the RAM is too slow (it also needs more voltage, current and cooling for more clock) ,...
Also an important point the cooling.
When your cooling is dusty you may have some degrees more temperature ...
So it worked when you computer was new and clean, and now ...
For the fun races I prefer short tracks
I also prefer slow cars for this