I think my power supply is dead

Last night, in the middle of a game, my computer just went dead and
refused to boot up. I think the problem may be the power supply (450W,
made by "Rhycom" if you've ever heard of them). I've removed the power
supply from the case and tried plugging it in and nothing happens. I
just want to confirm my theory that the power supply is dead: regular
power supplies, when disconnected from everything but power, should
still at least whir up their fans, right? Or does the power supply need
ot be attached to the mobo for the fans to work (in which case it may
not be my power supply that's dead?)

Thanks a lot for the help.

P.S. And no, I'm not stupid, I made sure the switch was on the "on"
position and the circuit set to 110V but still, nothing happened.