Isn't that special! I'm messing with my new P5B-Plus board today. The board way overclocks (PC-4200) and overtimes (5-5-5-15) my memory by default, so I set it to PC-5300 and 3-3-3-10 where it belongs. Turns out my \"improvements\" actually hurt latency performance, according to Sandra and PCWizard benchmarks.
I did some Googling and apparently this weird behavior is common for the P5B series of boards, although unexplained AFAIK. My best timings so far are 4-4-4-10.
Also beware synthetic benchmarks, they don't always behave correctly. If it really is a problem with the board, there should be a BIOS update to fix it soon. Load up a copy of CPU-Z and find out if the timings you set in BIOS are actually taking or if BIOS is screwing up.
