It took me ages to get both the 1600s to run I have no idea why I decided to upgrade, this board is finicky at best.
I have the Asus p8p67 pro rev 3.1 & corsair vengeance 1600 (2x4gb) & 1866 (2x8gb) is it possible to use them all simultaneously or should I just stick with the 16gb 1866 and make an attractive pen-holder out of the others? (I have the i5 2500k)
Turns out The A1 & A2 Dimm slots are just #$@%ed. I have 2 8gb @ 1866 & 2 4gb @ 1600. I can run one of each in B1& B2 or both of either pair. but not even a single runs in A1 or A2. It breaks my heart but now I have to RMA the board.