It's when the components are getting seriously hot (>80º) that this matters. I wasn't thinking of CPUs. Power switches with serious amps going through them can get seriously hot. There's an element of negative feedback, because the forward voltage across the devices (Vf) gets lower, so the wattage reduces. CPUs at the same levels would have shut down. It's the conflict of good design vs good appearances. Many of those go to 200ºC junction temperature, and the junctions are all big & clunky.

That said, I have seen thermal paste fully dried on CPUs, but not in your regular pc.

i thought so myself too, there were temp differences like 1-3 Celsius.

thats not much though.