In futuremark 06 with my resolution at 1920x1200(the resolution I normally use), my FSB at 400MHz and using PC2 6400 Ballistix,(double sided micronD9), I scored 11369 @1:1, 800MHz 4,4,4,12 and 11390 @1:1.2, 960MHz 5,5,5,15. So maybe it's your RAM and not the mobo?
I just got my system built...