my system's are 1.6kwh?!

[Rjb82]

Overclocking to the max rarely gets you the most profits. Usually some minor undervolting is in order. On my single 7970 (air cooled) gaming comp, underclocking the RAM and going from 1200MHz @ 1250mV to 1050MHz @ 1050mV can be the difference of 380W down to 245W. I get ~90% of the hashrate for ~65% of the power cost.

these days us GPU folk need every BTC we can grab before having/asics!

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)

^ This. Last year I had 1 less Gpu, And my apartment is pretty decently insulated. We ran the A/C all but 2 days last winter. Had a pretty fatty credit with the electric company when summer rolled around. Not to mention the bill dropped to almost nothing. ($30/m vs $70/m i think)

[firefop]

these days us GPU folk need every BTC we can grab before having/asics!

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*