Yesterday I had some success with overclocking my recently aquired 533 G4. It would only grey screen at 667, but booted and runs well at 600. At this point it is only running 9.2.2 but I recieve Tiger today. OSX should make diagnosis much easier and hopefully add some stability. My goal is still 667 as I plan to boost the voltage and cool the cache chips. Right now it is air cooled, but I have the h2o sitting, waiting for its time to shine! Its still in the G4 case, but I also think the larger atx case I plan to use should help too. Ill try and update this weekend.