Powermac G5 won't start

Hey is the ppc based Powermac G5 old enough yet for discussion? I inherited a ppc based mac tower. It looks to be the last version prior to going to a Intel based processor. I set it up a couple of weeks ago (long enough to do a time machine backup) but when I started it up last night it doesn't seem to start and I can't quite match the observed symptoms with known troubleshooting hints. On plugging into power: I do here relays click inside. On pushbutton start: The power indication goes out immediately when letting go of the button. I hear the disk drive start. I can hear the fans start as well. After about 5 minutes the fans start speeding up faster and faster. (I pulled the plug at that point) I haven't found anything on the web about this particular symptom?. (at least the light not staying on) Any ideas? George Rachor Hillsboro, Oregon