Well, this is a tough call. Soyo says 500, which means at least the old Katmai core (512k of half speed, off die cache instead of 256k of full speed, on die cache) PIII 600 will work They simply neglected to update their compatbility table when new processors were released. And since that board is overclockable to at least 133MHz FSB, the old Katmai core PIII 600B will work.
Now as far as "E" and "EB" processors (Coppermine core), those can work, but might need a little "help" to work. You see, the oldest board designs didn't support core voltage detection below 1.8v, and all Coppermines are 1.75v or less. You could probably use a 1000EB, but you might need to raise the detected voltage to 1.80v or 1.85v. The easiest way to do that would be to buy a Socket 370 version and an adjustable voltage Slotket, such as the Abit Slotket III, Iwill Slocket II...Abit, MSI, and Aopen also made them. All are hard to find.
The second easiest way to raise the detected voltage is to buy an ordinary non-adjustable sloteket and a socket CPU, and make the adjustments through modification. See <A HREF="http://www.crashman.dns2go.com" target="_new">http://www.crashman.dns2go.com</A> for instructions on the modification.
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