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M.2 SSD and Beyond: What is Ahead for the M.2 Slot?

By ·Categories: I/O Embedded & IoT, Tech Explained·Published On: September 18th, 2020·3.7 min read·

There was a time, not that long ago, when mSATA was the standard for people looking to add compact, solid state storage to their hardware. In the same vein, mini PCIe is allowing easy expansion in smaller computers and on Mini-ITX motherboards. However, a new standard emerged that has been dramatically improving how we use internal expansion. This new standard, called M.2 (formally Next Generation Form Factor, or NGFF), is being utilized as a M.2 SSD hard drive in our Helix Series of Industrial Computers and Karbon Series of Rugged Industrial Computers.

What is M.2? What is M.2 used for? And how does M.2 work?


M.2 is physically different than Mini PCIe, meaning that older mSATA drives and expansion (like wireless cards) will not work in M.2. It is unique because the standard has a wide variety of sizes for its cards. Also, it has several different kinds of keys. Keys are notches in the card preventing you from plugging in the wrong kind of device. With several different lengths and many keys, it comes in dozens of different variations. At first glance this may seem like a superfluous and unnecessary change. However M.2 is so robust from a technological standpoint that it requires these multiple variations.


The technical reason behind the keys rests in the fact that M.2 can take advantage of the PCIe, USB, Display, Audio, I2C or SATA busses on the motherboard. The M.2 slot usage determines the key, preventing an incompatible card from plugging into a motherboard. Some cards with multiple usages receive multiple keys. There are 4 common types of keys in usage today, each being assigned a letter for identification. The table below shows how each of those keys varies:

M.2 Keying Chart

There are emerging keys slated for future development as the M.2 form factor continues to show its versatility.


So what does all of this keying and bus interoperability mean for the average computer? In a nutshell it is leading to faster, more flexible and more available storage and expansion than previous solutions. As an example, take SSDs. Before M.2, SSDs were working off of the SATA bus. The latest SATA technology can transfer data at a max of 6Gb/s (Six gigabits per second). This is pretty fast, but not even close to PCIe. PCIe 4.0 can transfer data at 16Gb/s per lane (the number after the “x” in PCIe is the number of lanes, so PCIe x2 has two lanes). This means that a PCIe 4.0 based M.2 SSD drive can transfer data at up to 10x the speed of a traditional SSD. These same improvements are true for other expansion devices as well.

M.2 Speed Graph


When the technology launched, there were some issues with general lack of support for M.2 SSD hard drives. mSATA hard drives were well established and many motherboards were not compatible with the latest expansion ports. As form factors continue to shrink, and hard drive capacities climb, M.2 continues to establish itself as a standard, particularly for SSDs installed on Intel and AMD-based NUC form factor systems.

So what lies ahead for the M.2 slot? M.2-based wireless cards are providing WiFi, 4G, and Bluetooth capabilities, often including a combination of these technologies in a single card. Builders are also tapping into the M.2 slot to create additional I/O options, including COM, LAN, USB ports and more.

Though Graphics Processing Units (GPUs) generally have higher power requirements than available via the M.2 port, Visual Processing Units (VPUs) are gaining popularity. GPUs and VPUs have a number of key differences. The compact size and power efficiency of VPUs are allowing for smaller computers to process visual information, accelerate Deep Learning and power Artificial Intelligence efforts via the M.2 port.


The incredible speed of data transfer, diminutive size, and flexibility of the M.2 expansion slot makes it a perfect match for our newest series of OnLogic computers.

We are excited to see how the next generation of devices take advantage of this powerful technology to push the envelope on speed and size.


This blog was originally posted on March 25th, 2015. It was updated for content on September 18th, 2020.


About the Author: OnLogic

OnLogic is a global industrial computer manufacturer that designs highly-configurable, solution-focused computers engineered for reliability for the IoT edge.
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One Comment

  1. Jim Eddy November 22, 2021 at 6:35 am

    Thank you for sharing an informative article. This article is helped me to understand M.2 even better.

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