My PowerMac G5 fans hardly ever speed up. I mean they certainly never go full speed or ever close how they sometimes behave on start up. I never get the jet speed noise. Even when I am rendering a movie in FCP, I hardly hear the fans. Right now on idle, iStat pro reports CPU A being 58C and CPU B being 56C. Yet, the fans are still only 400RPM both CPUS Intake/Outake. Anyone know why this is?