Dual 867 MDD G4 won't boot

[kirkbross]

G4 won't boot. No startup chime. Power button light goes off right after I power it on. Fans go on and soon switch to high / fast mode.

Tried everything imaginable -- removing all cards, RAM swapping, PMU reset, bought a new 3.6v PMU battery... everything on this forum (I think) except buying a new power supply which I'm trying to avoid.

Is that my next step, and if so recommendations on where to buy?

Is there a way to confirm it's the PSU before I buy a refurbished one?

 

[666sheep]

Symptoms you've described are indicating logic board or CPU fail, not PSU.
Check CPU heatsink, maybe screws were loosen a little. It's enough to damage CPU during transport. Remove old thermal paste, check CPU cores and whole daughtercard for physical damages. Reseat CPU carefully, apply new thermal paste.

To test PSU, check voltages with multimeter. To power PSU on without computer's power button, just bridge PWON with nearest GND and plug PSU to power source. http://www.outofspec.com/frankenmac/wire.shtml