Why can't I use my PCIeNVMe SSD for storage?

2 slot is just a plain x4 slot, they look exactly the same to the host The only way you can know for sure is if you have an slot already or

is a form factor, there are a few variants for different applications, but the variant we are interested in for NVME SSDs is M key This

pcie 40 in 30 slot Reviewing the AMPCOM NVME SSD to PCIe Adapter Card, 64Gbps SSD X4

pcie slot length 2 M key slot is compatible with both B+M key SSD and M key SSD The last but not least, you should check whether the slot supports PCIe (