Most people have to run 2T with this board, even with good ram, and no OC. From benchmarks I've ran its a 2-3% performance hit, but its completely stable whereas 1T would would crash my games.

I use DDR 400 setting 3-3-3-8 2T. with fsb at 315.



Setup like this I'm scoring nearly 30k in 3dmark01se with a 6600gt.