Coppermine 600E @ 840 MHz. Not so amazing, but really fast for the MHz since it's on 140 MHz on a BX board. I especially like the 93 MHz AGP bus... almost 3x AGP...
Rock stable on a nice Tekram board, by the way. Only annoyance with my sytem is that the memory on my Leadtek DDR soesn't want to run without artifacts above 320 MHz (even when not on an overclocked AGP bus, that is).