New
#31
I believe this is how this works. When the computer is in hibernation, it is not completely off. For example, the real time clock has to keep running. There is enough memory available in firmware to record the next wakeup, so that's all it needs to know. The power drain is very small. On my fat desktop PC, the hibernate power consumption is spec'ed at 0.6 W.
When the computer is turned "off", whether that is still the case might depend on the motherboard (real time clock still has to run, though); I'm not sure. Note that for a momentary-contact power switch to work, there has to be a source of voltage, so the machine cannot ever be 100% off, although that voltage can come from the cmos battery if the machine has one. Not sure if modern laptops bother with a separate cmos battery.
--peter