You don't turn off the power to the dry cabi, leave it on 24/7. Its' power consumption is very low, about 5W, so don't worry about the electrical bill.
The PSU's sold in SLS are a minimum of 300 watts these days... And with the number of HDD's graphics and CPU drain, I wouldn't be surprised at the amount of power a personal computer does use up. :bsmilie:
Dun forget the amount of fans required to cool down and also the monitor.