a way to test the CPU is by taking it out along with the heatsink and plug all your power cables in this completes the circuit which allows the fans ot turn on
if your getting power out of your fans because the 24 pin is in then its probably the CPU i've had this issue. a simple swap for an e4500 and i was set to go
Er, maybe I should just gamble and order a PSU? It's covered by Newegg's 30 day refund so I guess it could be worth a shot but from what we've narrowed it down to, it is likely either the CPU or PSU, right?
More likely the motherboard than the CPU. sure go ahead and order a new power supply, if you shove it in and same problem occurs then you need to RMA or replace the motherboard.
what is your budget for the power supply?
Edit: 450 Watt Fortron will do nicely though it is far from your only choice.