I have an ASUS Sabertooth Z170 mark 1 MB and I cannot get my A2 DIMM slot to work. CPU is Intel i5 6600k, 8 GB Gskill DDR4 2133 as two 4 GB modules, PSU Corsair RM750x. The entire system worked on another MB but when I tried it on the Sabertooth it would only boot when one 4MB Gskill is in the B2 slot. I have reseated the CPU and the cooler to no avail. BIOS has not been flashed. Is this simply a bad DIMM slot?