I just finished tests after re-flashing my motherboard.
AIDA32 - mem test results:
read: 2510MB/s (now), 2280MB/s (before flash)
write: 1006MB/s (now), 430MB/s (before flash)
PCMark04 - mem test:
About 3100 now, earlier it was around 2100.
I'm not kidding... those are some MAD improvements right??!
Conclusion: ASUS P4S8X is one sure P.O.S board. It was only this december that ASUS released the - so called - "final" BIOS, making the board fully compatible w/ PC2700 mem:s.
I can now see all my previous issues w/ weird fps results in various benchmarks games having been fully 'healed'. Feels great, you can't imagine!