My PowerMac G5 will not start up. There is no startup chime, no display and the fans speed up and sound like and airplane after about 30 seconds. Can someone help?

Dual 1.8 by any chance?

Could be bad RAM, but more likely to be a dead logic board.

G5 has these hardware issues:

-- bad capacitors on logic board

-- bad capacitors in power supply

-- badly soldered video chip

-- "There were several Mac models with flat panel displays that had bad displays.

Most had serial numbers beginning with "W8"---the code for one specific factory.

This affected PowerBooks as well. If that's the case, the rest of the computer

is probably fine." by Allan Jones in

https://discussions.apple.com/thread/4922592?answerId=21630224022#21630224022

Google: g5 capacitor replacement kit

More info on capacitor replacement kits

http://jimwarholic.com/2008/07/how-to-repair-apple-imac-g5.php

http://thecapking.com/applg5.html