...this might be way too simplistic of a fix to work in this situation, but whenever my laptop gets overheated, it's usually because I switched my power settings to High Performance while it's still plugged in. Switching it back to Power Saver or Optimized cools it down right away.

Again, I'm not sure if this will work for your case (I know nothing about CPUs or fan replacements or motherboards /o\) but if nothing else, it's worth a try. (If you haven't tried it already. XD)