The power supply will only come on when there is a real load on it via pushing the power switch on the front connected to motherboard/fake load tester connected onto it, they are designed this way on purpose.
Edit: And I should add if you ever have to change ram, hard drive, video card... make sure that you either have turned off the switch on the back or pulled the cable to the supply as most motherboards are still powered when the machine is shut off.
Thanks a lot for that info. Now I can rest easy while I decide which MOBO to put inside this second Hackintosh.