asus prime a320m-k/csm

So I recently Purchased a Ryzen 5 4500 and a Asus Prime A320M-K/CSM and paired it with my GTX1650. I've noticed something really weird that I cant seem to figure out. So the main issue is I cannot use my full 16GB(2x8GB) of ram on the new System. PC wont POST if a RAM stick is in Slot A1 but...