I have the Z97 UD5 Black Edition variant and I am pleased with it... except for one issue. If I put 2 x 8GB in just the black slots, my computer runs fine but if I fill all four slots, my PC goes into an endless power up loop. Digital readout on board says C0 when all four RAM slots are filled. I am using Corsair Vengeance units recommended by Gigabyte (CMZ32GX3M4X1600C10) 1600MHZ. BIOS version of motherboard is F6. CPU is i7-4790. Any input regarding this matter would be appreciated.