Basically, heat is waste. A space heater is a resistor causing 0% efficient usage. If 500 watts of electricity go into a heater or a computer, 500 watts of he

Basically, heat is waste. A space heater is a resistor causing 0% efficient usage. If 500 watts of electricity go into a heater or a computer, 500 watts of heat will come out, minus some light from leds and screen, some electricity on the ethernet cable, and other of these ignorable things. If it does some usefull computation on the side, that's nice, but energy wise a 500 watt game computer is just as efficient as a 500 watt heater, if used for heating purposes.