I bought a Kill-A-Watt and have discovered that my desktop computer (21.5 inch iMac, circa 2010) is one of the worst power suckers in the house when I leave it on. However, even when it is off, every few seconds it pulses a little 0.03 or 0.04 amp. Is there something inside that needs this power to work properly, or can I just keep it unplugged/powerstrip turned off?