I'm running a P4S533 at 160 FSB, mem ratio 4:5 and so have my Samsung PC2700 at 200 mhz or DDR400. I dunno, it's possible about the PCI bus being off since I can boot cleanly at up to 164 no problem and I can even pass 3DMark2001, but Serious Sam 2nd Encounter hangs while loading the demo levels, or the demo loop kicks out to the menu. Perhaps a HD issue? I figured maybe 160 is the max of my CPU. But over 161 is a moot point since you are bound to bench higher at 160, 4:5 than 161-166 at 1:1.
I just burned in a single stick 512 MB Samsung original PC2700 and my results exceed expectations: so far I did DDR420 at 2-2-2-5-1 and at just default 2.5 voltage! It passed both the Docmem and Memtest burnin loop at 210 mhz (140 FSB, 4:6 mem ratio). More importantly, I booted into Win98SE and it runs all my 3D stress tests OK. Really seems too good to be true. I also have 2-256 MB sticks of same ram and those only did 2.5-2-2-6-1 at DDR400 and needed 2.9 volts!
Only problem is my Sandra marks at DDR400 is a little low: just over 2800. I should be getting 3000-3300 at 2-2-2-5-1. I suspect this SIS board is too new for Sandra 2002 so maybe it is not benching the memory correctly. I ran Memtest and see 3254 or something (but Memtest reads everybody's memory higher). I installed CPUZ to try to verify the memory settings but they are grayed out so it doesn't seem to recognize the memory or the board correctly.
I know the VR-Zone review did 209 at 2-2-2-5-1, but that was one 256 MB stick, mine is 512. Oh well, guess I'll take it and wait for a newer Sandra version to see if my scores go up.