I bought a 512mb stick of PC133 RAM for my sisters G4 a few days ago, and it arrived today. When I took out one of the 128s (previously there was 128, 128, 256, and 256 installed, all PC133) and popped in the 512. I checked About This Mac, and it only revealed 640mb, the 128 and the 256s, according to apple system profiler. I've tried the 512mb stick on its own in there, in all the slots, but every time I press the power button the G4 emits a very loud beep. IIRC, that beep means it can't find any RAM...
I then tried it in the Yikes! G4, and it works fine, but it only shows up as 256mb. I guess the biggest cards the Yikes! G4s can use is 256mb.
Any ideas? I'd really liks to have this card working in the sawtooth. I have tried it with no cards but the video card, with just one each of the other RAM cards, and with all the other RAM cards in difference slots.