My brother sent me his old CPU, MOBO, and RAM that he was using when he upgraded. He was using a GIGABYTE GA-Z87X-UD3H with G.SKILL RIPJAWS F3-12800CL9D-8GBRL 4Gx2. When i hooked everything up properly, it did not work with 2 sticks, but only with one. So I swapped them and they worked fine, each one individually, but not together. Can anyone tell me why please?