Thanks for the feedback so far guys.
Well I am trying to find another PSU to try but my old one's M/B connector is smaller than this so I doubt I will be able to find one to test with.
The thing is that the power supply came with the case and I'm afraid they may make me send back the whole thing which would be a pain.
I suppose I could always buy a cheap PSU to test with. But other than that any other recommendations? And I don't have access to a multimeter anymore ATF.