If it's a cold winter night and my office keeps the thermostat set to 65°F, does it really waste any power if I leave my computer running with the monitor off? Isn't my computer just helping to heat the office and taking away load from the heater? Bonus question: what if my computer has a giant spinning hammer that turns whenever the processor is running? Isn't all that energy (the heat from the motor, the air turbulence around the hammer, any sound from the hammer) eventually just going to heat? Bonus bonus question: What if I leave my monitor on?