A Short Discussion on NGFF M.2 NVMe

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There is so much confusion over M.2 SSDs.

Articles that are quite well written and informative never seem to explicitly state what the real world implications of a B-Key, M-Key, and B and M Keying is.

The first thing to remember that all the Keying has different implications for Sockets than it does for Devices (an SSD)

Important Items to Know

  • SSDs that fit into NGFF (Next Generation Form Factor, the old term) / M.2 (the new term) Sockets come in two "flavors": NVMe (Non Volatile Memory eXPRESS, which is newer) and non-NVMe (sometimes referred to as NGFF SSDs)
  • Both NVMe and NGFF SSDs can support USB, SATA / AHCI, and PCI-E (2 Lanes for NGFF and 4 Lanes for NVMe)*
  • Sockets that are M Keyed require an NVMe SSD


* Notice that the word can is in italics. This means a socket or device can support those protocols, it doesn't mean that they do.

Sockets (and what the keying indicates)

  • B-Key: Only supports SATA / AHCI (not PCI-E 2 Lane or 4 Lane) and USB
  • M-Key: Supports PCI-E, SATA / AHCI, and USB
  • B and M Key: There doesn't seem to be a socket that is keyed B and M

Devices (SSDs)

  • B-Key: Can / Has the potential (If implemented by the manufacturer, but not required to be implemented) for SATA / AHCI, PCI-E 2 Lane, and USB