I have: xp2100+ MSI KT4 Ultra 512 DDR 2100 Kingston 80 gig hdd Geforce2 64 meg The problem is that My 2100+ is running at a low fsb of 100 mhz, which is forcing it down to a 1500+ (1.3ghz aprox) When i changed my fsb to 133 like it should be set at the computer will not boot up, and i have to recent my motherboard to defaults with the jumpers. Is there a way to fix this? Is it a comflicting problem between my mb and processor? is the MB bad? Any help would be really appreciated... i can run it fine at 1500+ but i want it at top speed. Thanks for any information you have. By not boot up I mean nothing happens. It doesnt even start its boot up cycle. The graphics card screen doesnt come up, i cant enter bios. nothing.