OK so I have an old iMac Rev a motherboard and 256 mb of ram. the system was a 233 but I got a 333 chip for it. I will need info on ATX moding and overclocking (to 400 MHz).
I don't know anything about putting the iMac's mobo in an ATX case, but something about the overclocking. Be sure to check http://www.bekkoame.ne.jp/~t-imai/imace1.html , it's the authority on overclocking the G3 in my opinion. You have to be careful, though, the PPC750 base chip just won't put out more than 450Mhz, and I only got my REV. D to 400Mhz. Overclock with care!