Hey I just bought a 512mb memory module for my G4 which was already running 576 ram (two of 256 and one 64). I decided to add the 512 since i just installed Tiger and i want things to be smoother. I bought the right type of memory...168-pin pc100 but the problem now is that it doesnt recognize it, it doesnt post...whatever the jargon is. I've been told and keep seeing online over and over that the BUS has to be be 3X, that then and only then will the system recognize a 2GB memory limit. But I have no idea how to make my bus 3x. I do know that my current bus speed is 100mhz. I suppose some meddling will have to be done with the firmware? I just updated it successfully to the latest version (4.2.8f1), by the way, thinking that that would solve the problem...but the 512 is in and its still not being used by the computer. PLEASE HELP! i was scammed for a $335 lacie external hard drive on ebay recently and i really dont feel like accepting my defeat so early on with this purchase.... You are welcome to doctor my frustration. THANK YOU!