I have four sticks of ram working perfectly in this board. They're four sticks of 1gb Corsair XMS2 6400C4, running at 5-4-4-12 and 1000mhz 2T. The trick to getting them to overclock was to change the sub timing values off auto.
tRD = 5
tRC = 30
tWR = 5
tWTR = 7
the others are left on auto...