now we start to think a few steps smaller there are those very small transistors which always have a temperature peak when they are switched (load) so it needs a a tiny tiny little bit until they are cold and if we increase the V to much those temperature changes are higher
so 2 problems with high temperature changes
1 high mechanical load to the core
2 if we are close to 130°C in the middle from the core in a transistor for a part of ns it could be enough time for our energy to kill the CPU
and for the frozen pcb there is also a unused gpu, less temperature producing cash, different bus interfaces, and a imc also there is a connection from the head spreader to the pcb from the cpu all together way more square mm then the cores