Hi all, I recently got an asrock extreme 4 z77 mobo , intel 3570k and gskill 4gb x 2 1600MHZ(not dual channel, separate kit but same model, brought them together) I have update the mobo bios through internet. There are four ram slots, and they are a1,a2,b1,b2. In manual its said that a1,b1 - dual channel and a2 - b2 dual channel. But the problem is when add the ram to these following slots i am getting 55 error(that is memory not install). But the ram works only when i insert them in a1 and a2 slot. When try them in below configuration, i am getting 55 error 1. a1 , b1 2 b1, b2 3 a2,b2 4, b2,a1 5, a1,a2 6, a1,b2 I just want to know , whether my mobo is faulty. or everything is just fine.