I overclocked a Quadra 650 with a 33mhz 68040 processor to 42mhz 2 years ago when it was my webserver. It worked at 44mhz but crashed every 2-3 days so I had to bring it back down to 42. I also recently overclocked my 266mhz beige g3 to 315mhz with no problems. No crashes at all, seems to run fine. The temp didn't even rise. Anyone done any OC on their macs?