If there are NO errors when you run it at 600 then the drivers will most likely not take care of your problem. The new drivers are for PIII600s and above. The SB error you'll get if you need the drivers updated is blah, blah, blah EMU101...blah, blah, blah.
Try going into your BIOS and if your CAS setting are 2 then change them to CAS 3. Also what voltage are you running at? I have to run mine a 1.7v to hit 800 or more. To me it sounds like two things, memory or CPU. 600es are pretty good at hitting 800, have you tried swapping your memory out for better quality memory?
[This message has been edited by LaoChe (edited 05-22-2000).]