Hi, I'm really stuck on this one. I read one of the archived posts (http://forums.macrumors.com/archive/topic/25114-1.html) written by "grabberslasher", and followed the instructions in it (on software overclocking your bus speed from 100MHz to 133MHz). It worked! But now my 800 Mhz GigaDesigns upgrade is running at 533 (so says Apple's Profiler), when the jumpers on my upgrade card are set for 1.06GHz. I switched the jumpers to an 800MHz setting, and Profiler says I am still running 533 on those jumper settings. I then moved the jumpers to an 800MHz setting, and tested both settings with Cinebench '03. The 533MHz/1.06Ghz setting gives me about 760Mhz of speed (better than before the software overclock--I was getting 740Mhz). On the 533MHz/800Mhz setting, I clock 540MHz of speed. The computer is a Gigabit/Ethernet model, and I may be using PC100 RAM, though I'm not sure, because I bought it for an Apple (no speed specified), not as PC100 RAM. I'd love any help...any suggestions... Thanks!