All output power is thermal though. This is basic thermodynamics. A negligible amount of input power will be distributed outside of the CPU die which will be dissipated as heat a short distance away. Pray tell, what other energy form do you think this input is becoming anyway?
Indeed there will be some piezoelectric effect and some EM emissions on the order of micro watts compared to the 10s of watts burned by the CPU. But the poster I was replying to seemed quite confused about the fate of power in a CPU used for computation: It’s dissipated as heat.
Well some power is used to run the fans which ends up partly turning into kinetic energy of air leaving the case. Sure, that may also manifest itself as heat somewhere down the line, but not in a way that is relevant for this discussion (and indeed you have to draw the line somewhere).
It's probably fairly neglible though, probables less than a watt in most systems.
