try manualy setting the memory timings, and memory voltage, up it to 2.7 and set timings to 2.5-3-3-8 see if that works, if it does keep decreasing timings until you are satisfied. If not try 3-3-3-11, if that still fails then your board is probably faulty, though you could try reflashing the bios (original is on the cd) as maybe something got corrupted.