corsair vengeance lpx 16gb

I have just bought a brand new system and built myself. Once completed I have had a DRAM fault and was unable to post. I bought new RAM in the form of a LPX Corsair Vengance 2x8 16gb and found that I can post with only 1 ram stick in The A2 port. I was hoping someone could help me!

So after 2 weeks of research on here and elsewhere, my finger is finally hovering over that taunting 'Place Order' button. Just thought I'd get some final opinions before I take the plunge! Corsair Vengeance LPX 16GB (2x 8GB) 3000MHz DDR4 RAM AMD Ryzen 5 2600 CPU Adata XPG SX8200 480GB M.2-2280...