if i'm right in thinking, it does. it works because there is a wire from the psu that has power even when the pc is turned off, although it must be on at the wall.

the idea is, as you asked about previously, to allow the aquaero to bridge the PS_ON wire, to allow the motherboard to turn on the psu, it also allows the aquaero to turn off the pc instantly in the event of an alarm caused by either pump faliure, too hot a water temperature (ie radiator fan failure) or flow faliure (leak).

hope this clears it up for you