I recently installed my asus a7v333 with a 2600+ with 333 fsb. I've been doing some tests on the system and they are reporting that the external clock or fsb is at 133. I tried changing my multiplers from 16.0 at 133/33 to 13.0 at 166 to increase it to 166. I am under the impression that the system is suppose to be running at 333? But i don't see any combination of options that would put the system to that speed. When i set my bios to default it goes to 2133mhz 16.0 multiplier and 133/33 external frequency. Am I wrong thinking that it should be at 333? I am also running Pc2700 ddr ram.
I have an A7V333-RAID ( PCB ver. 1.02 ) and I've been running an unlocked and undervolted ( 1.3V ) Duron Morgan 1GHz @ 166MHz x 6 for quite a while now, I don't see any reason why your board won't run if you set the FSB to 166MHz using a top of the line Tbred B CPU.
BTW, 333MHz FSB don't actually exist, the clock is really set to 166MHz, ( the same logic apply to 266MHz which equals a 133MHz clock ) the FSB advertised is inflated 2x because Dual Data Rate SDRAM send two time as much data per clock as standard Synchronous Dynamic Random Access Memory BUT the clock signal frequency you set in the BIOS remains 166MHz.
Make sure your memory does support a 166MHz FSB ( PC2700 DDR SDRAM, Also Known As 333MHz ). Some high quality PC2100 ( 133MHz ) will run at PC2700 specs with no issues, cheaper modules will require that you lower your memory timings and some others simply won't run at all. Same goes for generic or cheap PC2700, some won't run at their rated speed if the timings are too agressive.
I suggest you supply us with additional information related to your memory brand, model and timings and the BIOS settings you tried. The A7V333 is one of the most agressive KT333 motherboard when it comes to memory timings, that's why some modules won't work in certain conditions. There's always a way to work around most issues, in my case, I managed to run Samsung PC2100 memory @ PC2700 by lowering some timings and my current stick of generic PC2700 can run on a 196MHz ( ! ) Front Side Bus.
Again, I'm willing to guide you trough this if you feed me with accurate info.