M.2 vs mSATA vs mPCIe — what’s the difference?

mSATA vs M.2 is a comparison of two generations of small plug-in card for embedded computers, with mPCIe (Mini PCIe) as the format both grew from. All three put a storage drive, wireless module or I/O card onto the motherboard without cables, which is why they are common in industrial PCs, single-board computers and gateways.

mPCIe is the PCI Express Mini Card, defined by PCI-SIG in 2003. It carries a single PCIe lane, USB 2.0 and SMBus, and on WWAN cards a SIM interface. mSATA (mini-SATA), launched by SATA-IO in 2009, uses the same card outline and edge connector but routes SATA signals instead. M.2, first called NGFF (Next Generation Form Factor), was standardized by PCI-SIG and SATA-IO in 2013 and was common on boards by around 2015.

On new designs, M.2 is the default. mPCIe and mSATA remain on many fielded systems, so engineers still meet them when replacing drives or modems.

mSATA, short for mini-SATA, is a solid-state drive format that puts a SATA SSD on a card the size of a Mini PCIe card. Its outline follows JEDEC’s MO-300 drawing, and it plugs into the same 52-pin socket as mPCIe, but the pins carry a SATA link, at up to 6 Gb/s on SATA III, instead of PCIe and USB.

mSATA was the usual small SSD in laptops, thin clients and fanless industrial computers through the early 2010s, until M.2 took over. Capacities typically reach 1 TB, and industrial mSATA drives are still made with wide temperature ratings and power loss protection for systems that have the socket. To the operating system an mSATA drive is an ordinary SATA SSD, so it needs no special drivers.

The full-size mPCIe and mSATA card is 30 × 50.95 mm and the half-size card is 30 × 26.8 mm; both are fixed by the standards. M.2 cards are 22 mm wide in a range of lengths, covered in our M.2 form factor sizes FAQ.

mSATA reused the mPCIe socket, so a card of either type fits a socket of either type. Nothing on the connector says which signals it carries. An mSATA SSD in an mPCIe-only socket is simply not detected, and an mPCIe card in an mSATA-only socket does nothing either. Some boards switched the socket between the two in the BIOS, others did not, and the result was a long tail of parts that fitted but did not work.

M.2 solved this with keying. Each socket has a notch in a set position for the interfaces it carries, and each card has matching cut-outs, so most wrong combinations will not physically fit. Our explainer on M.2 keying shows which key carries which interface.

When a system arrives without documentation, a few checks usually settle it.

Three changes moved new industrial boards to M.2.

Many fielded industrial computers, gateways and capture systems still use these slots, and they can stay in service for years. For storage, replacement mSATA SSDs are still made in industrial grades. For wireless, many 4G modems and Wi-Fi cards are still sold in mPCIe form. For video, our Mini PCIe capture cards suit boards with a spare mPCIe slot, while M.2 capture cards do the same job on newer boards.

Adapters exist from mSATA to M.2 SATA and from mPCIe to M.2, but they add a joint that can loosen under vibration and often do not fit the enclosure. On a long-lifecycle build it is usually better to move to a host with native M.2. Our guide to M.2 expansion slots covers what each key and size is used for on current boards.

We fit storage, wireless and capture cards to the slots each computer has as standard, and confirm every card is detected before the system ships. Send us the board or system you are working with and we will match the card to its slots.