nvm slotNVMe was desned for SSDs and communicates between the storage interface and the system’s CPU using hh-speed PCIe sockets without the limitations of form factor. The NVMe protocolThe ‘Key M’ or ‘M key’ slot is specifically for PCI-E SSDs aka NVME SSDs which are currently the fastest SSD type that one can buy. The ‘Key B’ slot is for M.2 SATA SSDs.