Depends on the motherboard, dude. Read the manual. There's a lot that could be going on.
Basically, if you don't understand the setting, and the machine is working good, don't mess with it. If you're experiencing problems, let us know about them.
It all depends on the SB, how the motherboard handles it, what the specs are of the components attached to it or running on it, etc etc. Write an email to the mobo manufs. and see what they say. They'll know best.