Comment by kmeisthax

Resistive heating generates heat: thus, it cannot generate more than 100% of the energy put into the resistor, because of conservation of energy.

In contrast, heat pumps move heat, so they can move more than the energy put into them. Even cold air (around freezing) has a lot of heat in it to siphon off.

If you're going to run 1MWh worth of compute anyway, then selling the waste heat is still a good idea. But if you weren't, a heat pump will get you more heat energy than a bank of computers with the same energy budget.