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Is it the 2.7ghz model?

Sounds like a coolant leak, bad thing is your computer is probably totally fried.


Good thing is I bet you can get Apple to give you a new Mac Pro if you do enough bitching.
 
In addition to the power supply it could have been an exploding capacitor on the motherboard or video card. It does happen from time to time. I had it happen on a 7600GT. If you open the system up look for bulges or breaks in the top part of any of the capacitors you can see. If it has occurred it'll be easy to spot.
 
http://www.mac-pro.com/s.nl/it.A/id.741/.f?sc=2&category=408


media.nl



About $200 bucks if it is the power supply.
 
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