What does the X4 mean in an PCIe Gen X4 NVME drive?

What does the X4 mean in an PCIe Gen X4 NVME drive? slot m 2 nvme cards with a B Key interface can only fit into a B Key host slot, and likewise for M Key But cards with a B+M Key design can fit in either slot wallet789 In this video I discuss the difference between an SSD and a NVME PCI-Ex4 SSD From how

slot wallet789 2 NVMe slots can be used for caching only? Storage purpose not allowed on them? Responses Sorted by Oldest

slot moyland PCIe SSDs 2 or 4 lanes) 1 x 67 pin key M slot 1 x 67 pin key B slot Interface: SATA PCIe Supports modules 2 adapter in a PCIe slot; SE350 data drive implementation Integrated on the system board On the ST50 V2, ST250 and SR250, a single drive