It might be easier if you give an example of which CPU and motherboard you are thinking of. But yes, you'd need the motherboard to be capable of supporting the CPU e.g. an E2200 has a FSB of 800mhz, a P35 based motherboard supports that FSB and all the way up to 1333mhz. Be aware though that just because the motherboard supports more than the required FSB it won't automatically support the CPU - check here with an example if you are unsure.