the spread spectrum turned on elimnate EMI, Electro Magnetic Interferance. Which can Make your processor Frequncy spike from the Magnetic Wave lengths. EMI can affect the CPU Freq. kind of like a really quick rev up for your CPU frequncy. it will make it go from 3.0HGz to anything that will make your PC lock up. So if you are palgued by EMI then keep in on. but that's only in a Very unusual circumstance.
It's bad for overclocking so turn it off.
Just like the "Auto Disable PCI Frequency" option. PCI frequency can cause mild EMI effects as well. So when "Enbled" it will turn Off UNUSED PCI slots that could cause EMI. Lessening the chance of that adversly affecting your OCing....
