[afreemanmd]

My Mac just died. It makes no noise at all. Pressing the start button does nothing. I opened it, disconnected the power supply connector to the main board and looked for voltage on any pins. Nothing. (the power supply was still plugged into 110 v) This seems to me that the power supply has died. Please tell me if this is absolutely true or if I am overlooking something. New supplies appear to be about $350 so it looks like I may be getting that new Mac Pro sooner rather than later. Thank you in advance for any help.

[roller]

I would guess you are right about the power supply. I just had one die in an older PMG4 in my lab (see sig), too. I am going to replace the power supply, however. I don't think they are quite that expensive. Seems like I have seen them for about half as much (US$).

[dowNNshift]

First reset your PMU and see if that works. A few knowledge base articles to check out:
Troubleshooting: My computer won't turn on

-- and --

Resetting Cuda/PMU on Power Mac G5, Power Mac G4, Power Macintosh G3

If no change after a PMU reset, with your multimeter and the power supply plugged in carefully check to see if you've gotta +5V trickle voltage coming from your power supply. On the main supply connector, Pin 1 is the +5V trickle and Pin 12 is a ground.