PowerMac G4 Upgrade Question

Well, they run at different bus speeds, the 450 runs at 100Mhz, and the 533 runs at 133Mhz. I don't know if that'll have any effect though, so I'd recommend checking out xlr8yourmac.com, they have a great section on processor upgrades and swaps.

 

First off, the motherboard of the 450 will only be able to operate at 100 mhz bus (unlikely you'd be able to overclock bus all the way to 133). That said, I think one of two things will happen. Either you'll plug in the processor, a it simply won't work. Or, you'll plug it in, and it will apply the 100 mhz bus and some multiplier to get the 533 to operate at a slower speed.