Read this:
(Quote)
What would you say if I told you their was a way to squeeze a few more megahertz out of that CPU of yours, even thought your at the maximum front side bus supported by your motherboard. Or maybe you’re not even at the maximum front side bus; maybe you just can’t seem to make the next step that the clock generator supports. Even if you have a motherboard with stepless FSB selection, this tweak could work for you. I have known about this sweet little tweak for years, and yet have never read an article anywhere about it’s usefulness to overclockers. And get this; almost every motherboard on the market is capable of this sweet little tweak.
Enough with the BS just tell us what the hell it is already!
There is a feature built in to most motherboards, accessible within the BIOS, called spread spectrum. It’s a simple little feature that alters the intensity of source frequency being sent to the clock generator in order to prevent radio signal interference. Basically it allows very very small changes in the FSB.
Here is a pic of the setting under the AWARD BIOS on an Abit VA6.
Some motherboards allow you to decrease as well as increase the spectrum. A decrease might just be up your ally if you can’t quite hit that next FSB. Just set it to decrease as much as the board allows, reboot, and increase the FSB to the next setting, and again reboot. If it worked, great! If not, back the FSB down, and set the spectrum to the highest increase the board will allow.
If you’re already at the maximum FSB and feel you can squeeze a few more megahertz out of the chip, the just increase the spectrum.
This is from,
Da OC Place
http://www.daocplace.com/index.php?article=spectrum