You don't use the BIOS to do it, you use the dip switches located on the CPU module to do it. Very easy to do...
I have heard that the reason that it is not clocked at 933mhz by default is that I'm paying for an 800mhz processor... Motorola couldn't deliver 800mhz parts apparently, and so now we have underclocked 933mhz parts. A side benefit to that is that it keeps the CPU cooler than it would be at 933mhz. I don't particularily like noise, so I don't really mind it running cooler so that I don't have to use a 5lb slug of copper and a 10,000RPM fan to keep it cool
I have heard that the G4 has to stay below 40C to work right.
