I have a New barton 2800+ 333FSB. I do not know what it Needs to be set in the bios I have a SOYO KT400 Dragon Ultra (platinum) I need the multiplier I think because it is being represented as a 2200+ and is only running at 1.67Ghz I just updated my BIOS so they can identify the Barton Core's Too. When I select 166 for the FSB Windows XP wont load and I cannot clock my PC3500 memory anything over 133 =\

"When I select 166 for the FSB Windows XP wont load" That implies that the mobo cannot handle 166, which it is supposed to, and rather than work too long on fixing it you might just take it back. The main thing that differentiates motherboard value is the fsb they can run at. When amd went from 100 to 133 on its cpus, via took forever to produce motherboards that could handle it. Via as the low cost chipset maker has always struggled to support the fsb of the then-current amd cpus (let alone overclocking them to an even higher fsb), and my guess is this is just another example of a via motherboard that is so lame it can't even run at 166, which is a no-brainer for all other current chipsets.

I overclocked an AMD XP 1800+ with that very same board. Set FSB at 166 left everything else in auto and presto. No problems for me. My guess is that you are making it too hard on yourself. Clear your CMOS and press delete when it starts doing it's memory check. Load optimized defaults. That board is very good at auto detecting the processor you have installed. In that same screen where you were trying to adjust the FSB, set performance to fast. Do a restart and just before it checks memory it will tell you what you FSB is. If it is not what it should be press delete to enter setup and go back to that screen and set FSB to 166 in manual and leave everything else in auto. If windows won't load then your PCI BUS divider is not set up properly. It needs to run at 33MHZ. So divide 33 into your FSB and set your divider accordingly. That would give you of 1/10. I think that the max you will be able to set it at is 1/8. But I'm not sure. That will make it run at 40mhz which is kind of on the edge, but should still work.

Oh! And to answer you question about the multiplier. You divide the processor speed by the FSB. Example: 2.5 gig divided by 333mhz= 7.5