I have two Samsung 970 Evo M.2 drives in my DiMM.2 slot. One is working happily and Samsung Magician shows it's interface as "PCIe Gen. 3 x 4" The other, in DiMM.2_2, shows "PCIe Gen. 1 x 4" and is much slower. This also happens to be my OS drive.
I can't find any documentation for these two slits on the riser being different. The DiMM.2 is set for CPU and I have a 44 lane processor. Can anyone point me in the right direction?