dungabee is right, however, for a little less noise, try the alpha 8045. it is BIG, but... it is MUCH quieter, because it uses a bigger fan. (bigger fan doesnt have to turn as fast to push the same amount of air). plus, its a bigger heatsink, so it doesnt require as much airflow to cool it... its a fairly quiet heatsink for as much as it cools.
the SK6 is a dope heatsink though.