Overclocking the intel?

i want to ask which of two needs cooling system, processor or motherboard's FSB. i have an intel. they say intel processors multiplier is locked and if you overclock it, the fsb is the one increasing speeds not the processor itself. Generally the fsb is located on the motherboard not in the processor. so changing the processors cooling systems is quite useless. but adding cooling systems to motherboard's fsb is somewhat usefull. RIGHT? because the one which is overclocked is the FSB.. thanks...