that's a slot 1 board, right? if so, you can use up to a PIII 1 GHz. They are available in both 100 MHz side bus and 133 MHz side configurations, but the 100's are very very rare and command a price premium. Your board will run stable at 133, and has an automatic 1/4 PCI divider, but you AGP bus will be overclocked. Almost all video cards can handle the overclock with zero problems, but if you use a really old video card, you might run into trouble.