Some mobos have weird identifications - this is prob 1 - 3 - 2 - 4 as to how to install (1-2) preferred for dual, then add to slot 3 for 3 sticks and 4 to fully populate.....you also see (from CPU 4-3-2-1 and 4-2-3-1 while most of them (and us) simply count from CPU 1-2-3-4