i bought an asus sabertooth mobo and it was not detecting any ram module put in slot b1. so I rmaed the board and now the new one does the same thing. I have tried different brands of ram, so ram is not the problem. Getting 2 bad mobos seems a little farfetched. So I am inclined to think its the cpu. But the ram works fine in slots a1 and c1 and i have no performance degrade by putting them there. I just cant use triple channel.