The Soyo 6BA+IV should support any PIIIXXXE 100mhz FSB. Just make sure you upgrade your bios first. It supports up to an 8X multiplier but since PIII's are multiplier locked it will pick up whatever the multiplier is on the processor. I would recommend staying away from EB(133mhz FSB) processors because the BX chipset doesn't officially support it and you don't have a lot of head room to overclock.. I was running a C566@850 8.5 multiplier and it ran perfectly. If you have quality Ram, heatsink and a video card that doesn't mind higher AGP bus speeds, then I'd recommend a PIII 700E CCO and overclock the crap out of it. I am currently running a PIII 700E@1008 stable on my BA+IV(Video card holding me back). Also the BA+III/IV/100 are basically the same boards except for: BA+IV added a Highpoint ATA66 Controller and the BA+100 added a ATA100 Raid controller.