It takes less time and would have taught more by not removing
supply AND using the so important 3.5 digit multimeter.

Procedu Motherboard turns power supply on and off. But
controller circuit requires power. When power supply is
plugged into wall receptacle, then purple wire (from power
supply to motherboard) provides 5.0 volts (within limits of
chart).

When power button is pressed, then motherboard controller
tells power supply to power on. Green wire is above 2.4 volts
when power supply should be off. Green wire should measure
less than 0.7 volts when power button is pressed - to command
power supply on.

Three components - power supply, motherboard controller, and
power switch. Using meter, discover which is or is not
working. Only then were you ready to replace something.
Voltage Wire Color Min V Max V
+5 V Red 4.75 V 5.25 V
-5 V White -4.75 V -5.25 V
+12 V Yellow 11.4 V 12.6 V
-12 V Blue -11.4 V -12.6 V
+3.3 V Orange 3.135 V 3.465 V
+5VSB Purple 4.75 5.25
!Power On Green 0.8 2.0
Power OK Gray 2.4 when power is good

BTW, if you did not pull plug from wall receptacle before
removing supply, then motherboard failure is a new
possibility.

Cyde Weys wrote:
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.