FSB speed while important isn't the determining factor for determining compatibility. It can always be under-clocked or overclocked if desired. Try searching the Epox site for the most up to date manual for the motherboard. Also make note of any motherboard BIOS updates. The socket also has to match, but that's a given. I know towards the end of the pentium 4 life cycle they started gaining true dual core with the highest end models (extreme) getting dual core plus hyperthreading. It may be a downgrade going from a celeron D to a single core pentium 4.