Also, if one uses their computers to keep their living quarters heated verses using a heater.. the electricity almost becomes "free" (or at least "very cheap", due to offsetting a normal heating bill)
I actually moved some mining equipment into the living room... cracked a window, and put 35watt box fan in a window at the other end of the house... I haven't had to turn the heater on yet (and it's hitting high 30s at night). The other day I came home to find my wife had closed the window in the front room... then turned on the AC because her gaming rig was overheating...
"Well why did you shut the window?"
"My feet were cold."
*sigh*