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Understanding M.2 SSD Interface In a Simple Way!

The most successful and popular SSD interface till this time is the M.2 interface. Also, known as NGFF (Next Generation Form Factor), the M.2 devices come in a very small form factor. It is basically the next and advanced version of mSATA. The mSATA form factor has a width of 30 mm whereas the M.2 became much more compact with a 22 mm width.

The M.2 ports have become very popular on desktop motherboards and laptop motherboards as well. Also, the M.2 SSDs are becoming cheaper day by day. But, lots of people have confusions about this form factor. Before starting, if you are here to clear your confusion about the M.2 SATA and M.2 NVMe form factor, you should read this article.

Now, without any further discussions, let’s understand the M.2 Form Factor in the easiest way possible.

When the mSATA launched back in 2009, people were considering it as a game-changer in the computer industry. But, after a very short time, the M.2 got launched with a great boom and it just dumps the hype of mSATA. The M.2 port was very small as compared to the SATA port. It was smaller than the mSATA as well. But, M.2 interface was capable of using the PCIe protocol which is the main reason why it very popular even after a decade.

The motherboard manufacturers can choose to equip these M.2 ports as a PCIe M.2, PCIe NVMe M.2, or a SATA M.2 port. According to these specifications, the M.2 SSDs can get connected to them.

There are different kinds of key specifications in the M.2 form factor which we are going to discuss below. But, for now, just understand that the M.2 interface is smaller yet fastest among all the available SSD interfaces.

The M.2 SSDs can come in five different sizes. Only the length of these devices will vary but the width will remain the same i.e. 22mm. The five main types of M.2 SSDs are as follows.

  1. 2230
  2. 2240
  3. 2260
  4. 2280
  5. 22110

For your information, the numbers after 22 with each size represent the total length of SSD in mm. The most popular M.2 Form-Factor size is 2280. This SSD is 22 mm wide and 80 mm long.

As we discussed earlier, an M.2 slot can have three different types of specifications.

  1. M.2 SATA (AHCI Protocol)
  2. M.2 PCIe (AHCI Protocol)
  3. M.2 PCIe (NVMe Protocol)

The M.2 PCIe using the NVMe protocol will be the fastest here. The overall bandwidth of this slot will be determined by the PCIe and NVMe versions. Also, the total number of physical PCIe lanes will impact the overall speed. You can know more about PCI Express here.

1.3.1 M.2 Version 1.0

The M.2 Ver 1.0 uses the SATA Bus where the data read/write speed is limited to 6Gbps or 600 MB/s. So, if you are connecting any SSD that offers more speed than that, this port will bottleneck the performance.

1.3.2 M.2 Version 2.0

The M.2 Version 2.0 overcomes the SATA bus’s speed limitations by equipping the M.2 port with a PCIe Gen2x2 lanes. With these specifications, this port will allow the devices to reach up to the speed of 10 Gbps or 1 GB/s.

1.3.3 M.2 Version 3.0

The M.2 Version 3.0 uses the PCIe Gen3x2 lanes and this is why it can reach up to the speeds of 16Gbps or 2 GB/s.

1.3.4 M.2 Version 4.0 (M.2 Ultra)

This one is the most popular M.2 version and currently working. These devices use the Gen3x4 PCIe lanes. With these specifications, these devices can reach up to the speed of 32 Gbps or 4 GB/s.

1.3.5 M.2 Version 5.0

These device uses the PCIe Gen4x4 Lanes and with these specs, the speed can reach up to 64 Gbps or 8 GB/s.

You will see two different types of M.2 ports and M.2 SSDs as well. The first one will have B-Key with a notch or a smaller slot on the left side. This slot can only work with the M.2 SATA SSD because all the M.2 PCIe and M.2 PCIe NVMe SSDs come with a smaller notch on the right end.

The other M.2 port will have an M-Key (means the edge connector will be placed on the right side). These ports will support M.2 SATA, M.2 PCIe, and M.2 PCIe NVMe SSDs as well.

See the image below for more.

M.2 Keying
Source: Wikimedia

Understanding M.2 keying is very important to make a wise purchase of a new SSD. The M.2 port with a B-Key is not compatible with the M-Key SSDs both physically and electrically. However, the M-Key M.2 ports will accept the B-Key SSDs (M.2 SATA SSD) both physically and electrically.

See the image below where I am installing an M.2 SATA SSD to an M.2 NVMe port.

Connecting an M.2 SATA SSD to an M.2 NVMe port

First of all, all M.2 devices are not faster than the SATA. In fact, the M.2 SATA SSD can achieve the speed up to 600 MB/s as per the SATA protocol.

The thing that makes M.2 fast and compatible with high-speed SSDs is the PCI Express. In addition, by using the NVM Express as the logical device interface, these data read/write speeds can reach sky heights. PCI Express overcomes the limitations of parallel connection interfaces such as PCI and AGP. The PCI Express or PCIe uses the serial connections by which we can achieve very high data read-write speeds. So, when we combine those PCIe lanes with the M.2 form factor and NVM Express, the capable devices can overcome most of the speed hurdles.

Because M.2 is a versatile form factor, computer manufacturers are using it to connect different kinds of devices. So, if your laptop or desktop motherboard has an M.2 port with AHCI protocol (SATA 3.0/ 600 MB/s), you can never achieve speeds more than the highest of SATA specifications. In fact, the physical port will not accept our high-speed NVMe SSD.

So, just by having the M.2 form factor, your SSD can never give you those 2GB/s or 3GB/s read/write speeds. The speed is determined by the protocol and the interface.

In simple words, if your M.2 SSD isn’t interfaced through the NVMe drive and protocoled by PCI Express, you just get the advantage for less space occupied. In other words, your M.2 SATA SSD will give you the same speed as a SATA 2.5″ but it will occupy lesser space because of its smaller form factor.

Just grab your manual and check the storage specifications. You will see whether your system has an M.2 port or not. The same manual will give you the details of whether the port supports NVMe or not along with the total supported storage space for that slot.

If you have a desktop, you can easily see the M.2 slot manually and check the key placement as we discussed above. If it’s M-Key, you can connect an M.2 NVMe or M.2 PCIe, otherwise, the B-Key slot will accept only an M.2 SATA SSD. In some cases, users make a mistake by installing an M.2 NVMe SSD inside the M.2 PCIe-only slot. This will also bottleneck your overall SSD performance. So, I would suggest you go through the manual anyway.

Another way is to get in touch with your manufacturer’s customer support and confirm everything from them.

Let me know about anything else you want to know about M.2.

Thanks for reading!