A faulty PSU would be reasonable - try a different one, if you have access to one.
I'm not sure where you are located; but, in Houston, there are dozens of electronics stores (I use Microcenter), and I've never had a problem borrowing a component off of the "open-box" shelf to test my systems - although, a certain amount of consumer-sales trust would need to be established first.
Z
Edit: To the more experienced folks around here: could it be possible that the PSU isn't bad, just under-powered to drive all of those components AND a water pump?