PCI G4: "real" sleep?


Hi folks.

I couldn't find any information at this, and what I did find elsewhere on the web was aimed for mirrored drive doors G4. Obviously, I don't have that kind of machine.

I'm using a rahter old PowerMac G4 (350MHz) with PCI graphics. I love this machine, but I would like to enjoy the benefits of not having to do a complete shutdown when all I really want is to "sleep" (read: sound powered off), usually during night hours.

I use Mac OS X Tiger 10.4.2, and of course I can put the computer to sleep via the Apple menu. And it sleeps. The problem is that the fan(s) inside are still spinning, doing really no change in noise whatsoever from the state of powered up.

Do anyone of you know how to fix this, if at all possible? Some rom update, OS X update, anything?
The G4 PCI machine does not support "deep sleep" like machines released after it do (G4 AGP, Quicksilver, MDD, G5, etc.). "Deep Sleep" includes the ability to go into a low-power, power-saving mode that includes spinning down hard drives, sleeping the monitors, eliminating CPU activity, and turning off the fans -- as close as you can get to a powered-off state without actually powering off.

Your fans inside will always spin unless the machine is powered off. "Sleep" on the G4 PCI machine simply spins down the hard drives and turns off the monitor.

While all PowerBook and iBook computers go into "deep sleep" when Sleep is selected, some older computers do not. Instead, the display turns off and the hard drive spins down, but many other components (including the processor) remain on.

Deep sleep is available on these computers:
All PowerBook computers
All iBook computers
Power Mac G4 (AGP Graphics) or later
iMac (Slot Loading) or later