Underclocking software for Mac OS X

From what I recall, OS X does that already. Hence why your laptop typically isn't as fast when running from the battery than the charger.

OS X has those energy settings, but there's not much control. XLR8 has a control panel that sold with their G4 upgrades that allowed you to set multiple bus settings. Normally that would correspond to manual settings you make on the board and daughter card, but I tried this on other machines without the upgrade. At the same board settings you could step down (or up) the bus speed multiplier settings, which correspondingly changed your proc speed. Thing is... I can't remember... pretty sure there was some modification to the kernel either for this control panel to work or for the system to recognize the cache, the speed of which also changes or is enabled/disabled. I don't really understand what happened with the whole Daystar* thing, but the customer support was excellent. They had me download betas until I could get my machine to boot (mucking around in single user mode moving kernal extensions back and forth can be nerve racking).

*mystery solved –– it never occurred to me to actually look and see... so it was Daystar all along, and xlr8 was in and out... they sure took over the Daystar brand for a number of years, but its nice to see Daystar is still around.