Make sure your MoBo supports PCIe bifurcation. If not, the lanes only read the first slotted NVMe.
Discussion
My mobo doesn't have any NVMe, which is why I was considering scrapping it. It does have lanes available for the pcie card and I bought a single drive card as I only need it for the OS on this machine. I'll live with spinning rust for the bulk storage, I want far too much space for my budget to put it all on flash.
I've been a drive speed junky since back when that meant WD Raptor 10k rpm sata drives. Very excited to get my desktop OS off of SATA.
I mean it's a BIOS specific feature. Those PCIe adaptors need bifurcation enabled in order to allow the x16 to be divided into 4, 4-lane PCIe NVMe slots. Without the Bifurcation option enabled in BIOS it will only show 1 NVMe storage device despite 4 being slotted.
I'm putting a single nvme drive on a pcie x4 card that has a single NVMe port and plugging it into an x4 slot, but that is a good point for others who may be copying me but with slightly different designs.
Ahh, I misunderstood. I have an older PC that I put a 16x PCIe NVMe 4 slot in, A 4x is a nice little expansion for an aux PCIe.