Slot m2 what. M2 or ssd which is better for the average mortal? Does my computer support M.2 slot

#M.2_key #M.2_socket_3 #M.2_type #M.2_socket #M.2_wifi #2230 #2242 #2260 #2280 #22110

M.2 (NGFF)– the general name of the form factor or physical interface for SSD drives, mobile WiFi adapters, 3G/4G modems and other computer components for miniature devices such as tablets, ultrabooks or nettops.

We have already talked about the new form factor using an example - this material can be found at the link.

However, M.2 was designed not only for SSDs, but also for WiFi, WiGig, Bluetooth adapters, GPS/GLONASS modules (GNSS), NFC modules, and other devices and sensors.

Previously, in mobile devices, the listed modules and adapters were connected using a mini PCI Express connector and had the popular full- or half-length Mini Card form factor. In turn, compact SSD drives had the same Mini Card form factor, but for the mSATA interface.

M.2 or Next Generation Form Factor replaced mSATA and mini PCIe, combining and expanding connectivity options, as it is capable of working with a large number of logical interfaces (Host Interface). In addition, the M.2 connector takes up less space in a mobile device, and there are several times more design options compared to the Mini Card due to the appearance of several M.2 (NGFF) sizes, depending on the width and height.

What you need to know about M.2?

• The M.2 (NGFF) specification includes devices that can be soldered to the motherboard, as well as a device that can be connected to various devices. The M.2 connector takes up 20% less space than the mini PCIe connector. The M.2 connector has a total of 67 pins, which can be separated by partitions - keys. Depending on the type of key, it is assumed that the connected devices are separated according to their intended purpose.


• The logical interfaces for the M.2 connector can be PCI Express, SATA, USB, Display Port, I2C, SDIO, UART and others.


• M.2 device sizes are standardized and grouped into types. The width of M.2 devices can be 12, 16, 22 or 30 millimeters. Length – 16, 26, 30, 38, 42, 60, 80 or 110 millimeters. For example, an M.2 SSD with a width of 22 mm and a length of 80 mm is designated "Type2280". (clearly shown in the schematic diagram of M.2 devices by size).


• The thickness of M.2 devices, more specifically the protruding components at the top and bottom, is also standardized. Devices can be either single-sided or double-sided - elements can be located on one side of the printed circuit board or on two.

Nomenclature designation for M.2 (NGFF) devices

Type XX XX- XX-X-X* Type XX XX-XX- X-X* Future Memory Interface (FMI)

M.2 key name (Key ID)	Number of involved contacts of the M.2 connector, pcs.	M.2 socket logical interface options
A	8-15	PCIe x2 / USB / I2C / DP x4
B	12-19	PCIe x2 / SATA / USB / PMC / IUM / SSIC / UART-I2C
C	16-23
D	20-27	Key reserved for future use
E	24-31	PCIe x2 / USB / I2C-ME / SDIO / UART / PCM
F	28-35
G	39-46	Will not be used for standard M.2 devices. Reserved for third party devices.
H	43-50	Key reserved for future use
J	47-54	Key reserved for future use
K	51-58	Key reserved for future use
L	55-62	Key reserved for future use
M	59-66	PCIe x4/SATA

* - If the second letter of the key is indicated, then the module is universal, compatible with two types of keys in the M.2 connector.

For example, it can be deciphered as follows: width – 22 mm, length 80 mm, double-sided layout, elements protrude 1.35 mm from the top and bottom, suitable for installation in a slot with B or M keys.

In general, manufacturers do not often indicate the nomenclature designation of M.2 modules. But, in fact, the designation can be compiled independently based on visual signs, as well as by simple measurements of the device.

Which M.2 (NGFF) devices use the M.2 connector with keys A, E, B, M?

What are Socket 1, Socket 2, Socket 3 as applied to M.2 (NGFF) devices?

Indeed, the concept of a socket for M.2 devices is encountered. The division principle is clearly shown in the following table:

	Soldered to the motherboard			For installation in M.2 connector
	M.2 module size	Height	Contacts are identical to the key	M.2 connector key	M.2 module size	Module height	M.2 connector key on the module
Socket 1 Typically, communication modules (WIFi adapters, Bluetooth, NFC, etc.)	1216	S1	E
				A, E	1630	S1, D1, S3, D3, D4	A, E, A+E
	2226	S3	E	A, E	2230	S1, D1, S3, D3, D4	A, E, A+E
	3026	S3	A	A, E	3030	S1, D1, S3, D3, D4	A, E, A+E
Socket 2 For compact 3G/4G M.2 modems, but other equipment may appear				B	3042	S1, D1, S3, D3, D4	B
Socket 2 For M.2 SSD and other equipment with a B+M universal key				B	2230	S2, D2, S3, D3, D5	B+M
				B	2242	S2, D2, S3, D3, D5	B+M
				B	2260	S2, D2, S3, D3, D5	B+M
				B	2280	S2, D2, S3, D3, D5	B+M
				B	22110	S2, D2, S3, D3, D5	B+M
Socket 3 Only for SSD drives with M.2 interface (at least for now)				M	2242	S2, D2, S3, D3, D5	M, B+M
				M	2260	S2, D2, S3, D3, D5	M, B+M
				M	2280	S2... D2, S3, D3, D5	M, B+M
				M	22110	S2... D2, S3, D3, D5	M, B+M

From the data in the table it can be seen that Any SSD with a B+M universal key can be installed in the M.2 M Key slot. In its turn It is physically impossible to install an SSD with an M key in slot B, even if the logical interface of the devices is the same.

It is for this reason that manufacturers of motherboards for installing SSDs make an M.2 connector with an M key and two logical interfaces to choose from - PCIe or SATA. But there are exceptions when the M.2 connector on the board is connected only to the PCIe bus or only to a SATA controller - you need to be more careful with this when choosing the right one.

Greetings to all, dear readers of the blog site! In 2002, the SATA interface appeared, which is now used to connect the vast majority of hard drives and SSDs. Over the past 16 years, it has been updated three times, while maintaining backward compatibility. In 2009, a compact version of this interface appeared - mSATA, which is located directly on the motherboard.

Support for Connector m2 on motherboards began in 2013. In terms of its purpose, it is very similar to mSATA, however, it allows you to bypass the bandwidth limitation of the SATA interface. Since the mSATA standard is based on SATA 3, its throughput is only 600 MB/sec, while modern SSDs already operate at speeds of 3000 MB/sec and higher.

This is what an SSD looks like in the M2 form factor

Using the M2 connector, you can install not only an SSD in your computer, but also other ngff devices: Wi-Fi cards, Bluetooth, NFC and GPS expansion cards. With this type of connection, you will get rid of numerous wires running from the drive to the motherboard. Thus, you will save space inside the system unit, improve its cooling and simplify maintenance.

SSD drives using the M2 connector are similar in appearance to RAM strips - they are just as thin and are inserted directly into the computer motherboard. It is noteworthy that initially the m 2 connector was used in laptops and netbooks, because their cases are thin enough to install full-size devices there. Then, the m2 connector began to be found on regular motherboards - on stationary PCs.

The m 2 connector uses an interface type such as PCI Express to communicate with the motherboard. Just don’t confuse it with the PCI Express connector itself, of which there may be several and which are located below the video card connector and are present even on older motherboards. This is a little different, although there are SSDs that connect via a PCIe port. And here’s what the M2 connector looks like on the motherboard:

Peculiarities

SSD drives designed for the M2 connector are available in different sizes: 2230, 2242, 2260, 2280 and 22110. The first two numbers indicate the width, and the next two numbers indicate the length (in millimeters). The longer the strip, the more chips you can place on it, and the greater the disk capacity. Despite such a variety of form factors, the most popular is 2280.

The m2 connector on modern motherboards may have different positions. We are talking about some “keys”. Again, we can draw an analogy with RAM strips: DDR3 memory differs from DDR2 in the location of the keys - small cutouts in the strips and the slots themselves, respectively. Same here, small cutouts can be located on the left and right sides of the port.

Connector m2 can have two keys: B and M. It turns out that they are not compatible with each other. However, you can find motherboards with a B + M (combined) connector. In addition to the PCIe interface, the m2 port also supports SATA mode. But the speed in SATA mode will be significantly lower than in PCI Express. The keys usually determine what type of interface will be used.

In conventional hard drives (HDD), the controller communicates with the operating system via the AHCI protocol. But, this protocol is not able to use all the capabilities of modern solid-state drives. This prompted the emergence of a new protocol called NVMe. The new protocol is characterized by low latency and allows you to perform more operations per second, while minimizing the load on the processor.

How to choose m2 SSD

When purchasing an SSD drive operating via the m2 interface, be sure to pay attention to the following things:

• Port size m2. Select a disk so that it can be installed in the motherboard, so that nothing rests anywhere.
• Key type - B, M, or combined. Both the motherboard and the SSD itself must have compatible keys. SATA m2 SSD drives are usually available with “M+B” keys, and PCIe m2 SSDs are available with “M” key.
• Interface version and number of lanes: PCI-E 2.0 x2 has a throughput of 8 Gbit/s, and PCI-E 3.0 x4 has a throughput of 3.2 GB/s.
• Which interface is supported - PCI Express or SATA. Of course, PCIe looks preferable because it allows you to work at higher speeds. The possibility of installing an M2 SSD in SATA mode should be indicated in the instructions for the motherboard.
• Support for the NVMe protocol is desirable. If it is not there, then AHCI will do.

An SSD drive that meets all the parameters will be much faster than one connected simply via SATA ports. This solution may be required in games and programs that require high read/write speeds from the disk. The best option would be a drive that uses the PCIe version 3 interface with four lanes and the NVMe protocol.

I am glad to meet you again, my dear readers. The subject of our conversation is the new M2 connector, which recently appeared on motherboards and, accordingly, about the devices installed in it.

And if earlier this topic was of interest to a narrow circle of advanced users, now every self-respecting buyer of a new computer or hardware is obliged to have this information and take into account modern computer trends.

Now the connector is not the weakest link

The emergence of a new connector for motherboard manufacturers is a serious and risky decision. After all, it must be supported by companies that manufacture components. In addition, there must be a real need for such a technical solution. Therefore, the story about the M2 should begin with a description of the reasons that prompted its development.

And here, friends, everything is banal and simple. Many of you know that SSD drives can significantly speed up your PC, providing almost instantaneous information exchange.

However, in practice, their capabilities are limited by the SATA connector, whose bandwidth is 600 MB/sec. Previously, this was plenty, but modern solid-state drives have already reached 2 GB/sec in read speed. Therefore, there was an urgent need to eliminate this bottleneck.

M2 – universal high-speed connection for different modules

Such a solution was found in the form of a new connector, originally called Next Generation Form Factor. In 2013 the name was changed to the simpler designation M.2. This connector first appeared on motherboards from Intel with H97 and Z97 chipsets designed for Haswell Refresh processors. In fact, the world saw physically and logically a completely new connector that has all the necessary qualities:

• Rapidity. M.2 has a data transfer speed of 3.9 Gb/s. And this is not a bad margin, considering the parameters of the best modern drives;
• Versatility. In addition to the SSD, you can connect Wi-Fi, Bluetooth, GPS navigation, digital radio, and high-speed radio communication devices (NFC, WiGig) through it. Also, through M2, individual PCs are combined into a global wireless WAN network.
• Compactness. The connector length is only 22 mm. Accordingly, the modules connected to it are small in size.

In addition, the use of the M2 connector eliminates the need for additional connection to the power supply. In general, the development turned out to be universal, promising and quite convenient to use.

Be careful, M2 connectors are different

Now let's look at it in detail.

First, let's look at the form factor. M2 is 67 contacts spaced half a millimeter apart. Quite a piece of jewelry work, but everything is compact and functional. Each of the contacts can withstand a current of 0.5 A and a load of 50 V.

In order to avoid messing up anything when connecting, the connector is provided with a key - a plug that cuts off part of the contacts. There are two possible combinations in M2:

• V-key. 6 contacts separated.
• M-key. The same, but with five.

The connected devices have a blade contact with a notch in the appropriate place. However, there are three options here: B, M and B+M, where the group of contacts has two separators: 6 contacts are separated on one edge, and 5 on the other. Accordingly, when choosing an SSD or other device for connection, you should take into account the type of key.

The M2 connector has one more secret regarding the supported protocols. Naturally, existing data transmission technologies were used in its design. Therefore, it supports USB 3.0, Display Port, I2C, Serial ATA 3.0, PCI Express 3.0 and others.

Yes, they can all be implemented in M2. But what exactly the motherboard supports is something that always needs to be clarified. Here you have a computer with M2, you bought an SSD with such a connector, but it is not detected. This can happen if the drive is designed for a slot, and the motherboard supports drives via PCI Express 4x.

The surprises may not end there. In addition to the nuances described above, the boards inserted into the M.2 connector have different sizes. As a rule, such modules are designated 2242, 2260, 2280, where 22 is their width (corresponding to the connector) and the remaining numbers are the length in mm. Therefore, neglecting this value may result in your drive not fitting into a compact case or interfering with other PC components.

Results

To summarize, we can safely say that in the form of the M2 connector, the developers have created a powerful tool for implementing all kinds of technical solutions based on high-speed information exchange.

Users will get more compact and faster computers. I do not exclude that over time this connector will be modified and improved (after all, there are limiting nuances in its operation), but, be that as it may, today it is its presence on the motherboard that determines the potential of your PC.

But what if you have a disk on the M2 and buying a new motherboard doesn’t fit into your budget plans? There is a way out in this situation, and this is a simple and cheap adapter to USB 3.0.

Here's a good option for example: https://ru.aliexpress.com/item/NI5LUSB-3-0-to-M-2-SSD

Or here: https://ru.aliexpress.com/item/m2-hdd-box

This concludes our conversation about the M2 connector.

I am sure that its “hero” has interested you and you will be able to enjoy the benefits of using it.

I wish you all good luck, progress and prosperity.

They are becoming increasingly popular due to their many benefits. They are miniature in size and do not take up much space in a laptop, mini-PC or desktop computer case (they are installed directly on the motherboard), however, they allow you to achieve speeds inaccessible to “regular” 2.5-inch SSDs.

You need to know that M.2 SSD drives are available in various formats (can vary in length), as well as two main variations - those using the SATA interface (cheaper and slower) and those using the PCI Express / NVMe interface (more expensive and faster). The currently used SATA interface allows a maximum throughput of 6 Gb/s, while PCIe x4 is up to 32 Gb/s, so the difference in performance can be very large, as well as the price.

By the way, it’s worth mentioning Intel Optane memory (not to be confused with Intel Optane SSD), which has an M.2 media format, but serves to speed up the operation of HDDs. This technology only works on newer Intel platforms, but it works surprisingly well, allowing for significant increases in magnetic disk speeds.

M.2 connectors on motherboards may support both standards, or only one - this is worth checking before purchasing so that, for example, you do not try to install a PCIe/NVMe drive into an M.2 connector that only supports the SATA standard. It is worth noting that you can also connect M.2 PCIe drives to the U.2 port (via an adapter) and to the PCI Express slot.

Below are presented as most efficient SSD designs, which use the PCI Express x4 3.0 (NVMe) bus, and cheaper/less powerful models that use the SATA standard.

Inexpensive M.2 SSD drive

Among the cheap M.2 drives you can find designs that use SATA and PCIe. The capabilities of the former are close to 2.5-inch SSDs, but their size is in their favor, as well as the fact that some computers may not support M.2 NVMe drives.

WD Green PC SSD G2 (120 GB)

The WD Green PC SSD G2 series is one of the cheapest M.2 options. Based on the SATA interface, the performance of the 120 GB model reaches 545 MB/s when reading and 430 MB/s when writing data. The manufacturer used a 4-channel Silicon Motion SM2246XT controller and Toshiba 3D TLC NAND memory cells (but without cache memory).

Main characteristics:

• Disc format: M.2 2280
• Capacity: 120 GB
• Disk interface: SATA III
• Write speed: 430 MB/sec
• Read speed: 545 MB/sec
• Memory cells: Toshiba 3D TLC NAND

ADATA XPG SX6000 (128 GB)

ADATA XPG SX6000 is, in turn, one of the cheapest M.2 SSD media using PCIe 3.0 x2. The manufacturer used a 4-channel Realtek RTS5760 controller and modern 3D TLC NAND memory here. Claimed speeds reach 730/660 MB/sec. A warranty of up to 5 years is provided, but is limited by TBW (75 TB data recording).

It is worth noting that the 256 GB and 512 GB models are not only affordable, but also much faster (1000/800 MB/s).

Main characteristics:

• Disc format: M.2
• Capacity: 128 GB
• Interface: PCI-Express 3.0 x2 (NVMe), PCIe 3.0 x2/NVMe 1.2
• Write speed: 660 MB/sec
• Read speed: 730 MB/sec

ADATA Ultimate SU800 M.2 (250 GB)

ADATA Ultimate SU800 M.2 drives have a very good price-to-features ratio. Modern 3D TLC Nand memory cells and a 4-channel Silicon Motion SM2258 controller are used.

This is a drive with a SATA interface, so the performance is identical to the 2.5-inch version - read speeds reach 560 MB/s and write speeds reach 520 MB/s. A 3-year warranty is provided, but is not limited by the TBW factor. Along with the disc we receive the Acronis True Image HD software package.

Main characteristics:

• Capacity: 256 GB
• Interface: SATA III M.2
• Write speed: 520 MB/s
• Read speed: 560 MB/s
• Memory cells: Micron 3D TLC NAND

M.2 SSD for Laptop

In the case of laptops, this will often be the only drive in the computer, so it is worth taking care of sufficient capacity - you should not invest in an SSD with a capacity below 240/256 GB. We must also pay attention to the type of interface - whether the media supports the SATA or PCIe interface, and what format (longer, 2280, or shorter, 2260 or 2242).

Crucial MX500 M.2 (250 GB)

The latest generation of SATA SSDs from Crucial, the MX500 is another successful blow to the mid-range performance segment. The M.2 version of the drive has fairly good performance, and the stated speeds reach 560 MB/s when reading and 510 MB/s when writing data. Crucial provides a 5-year warranty (limited to 100TB TBW).

Main characteristics:

• Disc format: M.2 2280
• Capacity: 250 GB
• Interface: SATA III
• Write speed: 510 MB/s
• Read speed: 560 MB/s
• Memory cells: Micron 3D TLC NAND

Transcend MTS420 (240 GB)

Transcend MTS420 in 240GB version- This is a very good offer for users who need M.2 media in the small 2242 format. The manufacturer specified maximum speeds of 560 MB/s for reading and 500 MB/s for writing. It is worth noting that many other discs in this format have worse characteristics. The manufacturer gives it a 3-year warranty.

Main characteristics:

• Disc format: M.2 2242
• Capacity: 240 GB
• Interface: SATA III
• Write speed: 500 MB/s
• Read speed: 560 MB/s
• Memory cells: Micron 3D TLC NAND

ADATA XPG SX8200 (480 GB)

This is a good offer for laptop users who can install SSD media in M.2 2280 PCIe format in their machine. If the laptop boasts an M.2 PCIe 3.0 x4 connector, the speeds will be 3200 MB/s when reading and 1700 MB/s when writing. The XPG SX8200 drive is covered by a 5-year manufacturer's warranty.

Main characteristics:

• Disc format: M.2 2280
• Capacity: 480 GB
• Write speed: 1700 MB/s
• Read speed: 3200 MB/s
• Memory cells: Micron 3D TLC NAND

Best M.2 SSDs

Best M.2 drives have amazing performance, and their efficiency approaches the limits of the PCI Express interface (the best drive presented here reaches maximum speed 3.5 GB per second). Obviously this is reflected in the high price. Such discs can be recommended to professionals, for example, working with complex video projects in 4K resolution.

GOODRAM IRDM Ultimate (480 GB)

IRDM Ultimate 480 GB is a good offer for more demanding users. What’s important is that the kit includes an adapter for the PCI Express slot. The manufacturer also installed a heat sink that protects the disk from overheating. On board is an 8-channel Phison PS5007-E7 controller and durable Toshiba A19 MLC NAND memory cells. Maximum speeds reach 2900/2200 MB/s. The IRDM Ultimate series is covered by a 5-year manufacturer's warranty with no data recording limitation.

Main characteristics:

• Disc format: M.2 2280 / AiC HHHL
• Capacity: 480 GB
• Interface: PCIe 3.0 x4/NVMe 1.2
• Write speed: 2200 MB/s
• Read speed: 2900 MB/s
• Memory cells:Toshiba A19 MLC NAND

Intel SSD 760p (512 GB)

Intel SSD 760p is an efficient SSD for desktops and modern laptops using the M.2 connector and PCIe 3.0 x4 interface. On board is a Silicon Motion SM2262 controller and IMFT 3D TLC NAND memory cells. Maximum speeds are 3230 MB/s for reading and 1625 MB/s for writing. The manufacturer provides a 5-year warranty for the drives, but limited to TBW (288 TB of recording).

Main characteristics:

• Disc format: M.2
• Capacity: 512 GB
• Interface: PCI-Express 3.0 x4 (NVMe)
• Write speed: 1625 MB/s
• Read speed: 3230 MB/s
• Memory cells: IMFT 3D TLC NAND

Samsung SSD 970 EVO (500 GB)

SSD 970 EVO is the third generation of high-speed M.2 media with PCIe interface from Samsung. The 970 EVO models are designed for users who are looking for very fast, but not top-end solutions - we will find this combination in the 970 PRO models. The stated read speed reaches 3400 MB/s, and write speed – 2300 MB/s. The 970 EVO series hard drives come with a 5-year manufacturer's warranty - remember that the previous 960 EVO models only had a 3-year warranty.

Main characteristics:

• Disc format: M.2 2280
• Capacity: 500 GB
• Interface: PCIe 3.0 x4/NVMe 1.3
• Write speed: 2300 MB/s
• Read speed: 3400 MB/s
• Memory cells: Samsung TLC V-NAND

Samsung SSD 970 PRO (1 TB)

Samsung 970 PRO 512 GB is an absolutely top M.2 PCIe SSD carrier designed for professionals. The manufacturer used ultra-reliable MLC V-NAND memory here, so users do not have to worry about their data. It is difficult to squeeze even more out of the PCIe 3.0 x4 interface, so the media reaches speeds of 3500 MB/s for reading and 2300 MB/s for writing. The 970 PRO series hard drives come with a 5-year manufacturer's warranty.

Main characteristics:

• Disc format: M.2 2280
• Capacity: 1000 GB
• Interface: PCIe 3.0 x4/NVMe 1.3
• Write speed: 2700 MB/s
• Read speed: 3500 MB/s
• Memory cells: Samsung MLC V-NAND

M.2 connector (formerly known as Next Generation Form Factor and NGFF) is a specification included in the SATA 3.2 standard for computer devices and their connectors, approved by the Serial ATA International Organization (SATA-IO) for tablets and thin computers. Created to replace the already outdated SATA, mSATA and Mini PCI-E formats. The key innovation of M.2 (NGFF) is support for data transfer via PCI Express 3.0 with a total theoretical throughput of up to 32 Gbps. Which is almost 6 times more than the SATA 3.0 standard allowed.

M.2 expansion cards can provide various functions, for example: Wi-Fi, Bluetooth, satellite navigation, NFC radio, digital radio, Wireless Gigabit Alliance (WiGig), Wireless WAN (WWAN) and others. Fast and compact solid-state flash drives (SSDs) are often manufactured in the form of M.2 modules.

The use of a new device format made it possible to use the DevSleep minimum power consumption mode, the Transitional Energy Reporting power management mechanism, the Hybrid Information mechanism (increasing the efficiency of data caching in hybrid drives) and Rebuild Assist (a function that speeds up the process of data recovery in RAID arrays).

Form factor and keys.

Simply put, M.2 is a mobile variant of the SATA Express protocol described in the SATA 3.2 specification for tablets and thin computers. This interface can be compatible with devices using SATA, PCI Express, USB 3.0, I2C and others protocols. M.2 supports up to four PCI Express 3.0 lanes, while SATA Express connectors transfer data over only two PCI Express 2.0 lanes. The boards have 4 widths (12, 16, 22 and 30 mm) and 8 lengths (16, 26, 30, 38, 42, 60, 80 and 110 mm).

In addition to the length and width of devices connected to M.2, standards for the thickness of components on the board are described. Also, single-sided and double-sided mounting options (Single Sided and Double Sided), divided into 8 more types. For a more convenient understanding, I will provide a table below:

The thickness of the components on the board of the device connected to M.2 (dimensions are indicated in millimeters).

Type	Above	From below
S1	1.20	Not allowed
S2	1.35	Not allowed
S3	1.50	Not allowed
D1	1.20	1.35
D2	1.35	1.35
D3	1.50	1.35
D4	1.50	0.70
D5	1.50	1.50

To indicate the M.2 type, devices are marked with a code according to the scheme WWLL-HH-K-K or WWLL-HH-K, where WW and LL are the dimensions of the module in width and length in millimeters. HH encodes whether the module is single-sided or double-sided, as well as the maximum allowable height (thickness) of the components placed on it, for example “D2”. Part K-K indicates key cuts; if the module uses only one key, one letter K is used. If K-K is used, then the module has 2 keys.

A diagram with a detailed explanation of all marking meanings indicating the values.

As of 2018, the most popular sizes are defined as: width 22 mm, length 80 or 60 mm (M.2-2280 and M.2-2260), less often 42 mm. Many early M.2 drives and motherboards used the SATA interface, the most popular dongles for them are B(SATA and PCIe x2). Modern motherboards implement the M.2 PCI Express 3.0 x4 slot and the corresponding key M(SATA and PCIe x4). Devices designed for use in M-keyed sockets are not electrically compatible with B-keyed sockets, and vice versa, unless otherwise stated. Although it is not uncommon, as practice shows, they are physically compatible (if turned over). To connect expansion cards, such as WiFi, modules of size 1630 and 2230 and dongles are used A or E.

M.2 - the board must not only fit in size, but also have a key arrangement compatible with the slot. The keys limit mechanical compatibility between different connectors and M.2 form factor cards and prevent drives from being installed incorrectly in the slot.

Actually, before purchasing an expansion card, you need to check with the manufacturer about the type of connector and compatible dimensions (length, width, thickness, single-sided and double-sided).

What are Socket 1, Socket 2, Socket 3 as applied to M.2 (NGFF) devices?

Indeed, the concept of a socket also appears for M.2 devices. I’m thinking of creating groups of M.2 connectors on Socket 1,2,3 for a simplified separation of devices that are not compatible with each other. Formally dividing all types of devices into 3 easy-to-understand types.

The division principle is clearly shown in the following table:

	For installation in M.2 connector
	Connector key	Module size	Module thickness	Connector key on module
Socket 1 Typically, communication modules (WIFi adapters, Bluetooth, NFC, etc.)
	A, E	1630	S1, D1, S3, D3, D4	A, E, A+E
	A, E	2230	S1, D1, S3, D3, D4	A, E, A+E
	A, E	3030	S1, D1, S3, D3, D4	A, E, A+E
Socket 2 For compact 3G/4G M.2 modems, but other equipment may appear	B	3042	S1, D1, S3, D3, D4	B
Socket 2 For M.2 SSD and other equipment with a B+M universal key	B	2230	S2, D2, S3, D3, D5	B+M
	B	2242	S2, D2, S3, D3, D5	B+M
	B	2260	S2, D2, S3, D3, D5	B+M
	B	2280	S2, D2, S3, D3, D5	B+M
	B	22110	S2, D2, S3, D3, D5	B+M
Socket 3 For M.2 SSD and other equipment with M key and B+M universal key	M	2242	S2, D2, S3, D3, D5	M, B+M
	M	2260	S2, D2, S3, D3, D5	M, B+M
	M	2280	S2… D2, S3, D3, D5	M, B+M
	M	22110	S2… D2, S3, D3, D5	M, B+M

Let's look at an example based on real online stores:

SSD drive SAMSUNG M.2 860 EVO 250 GB M.2 2280 SATA III (MZ-N6E250BW)

From the description it is clear that we have a Samsung SSD with a capacity of 250Gb, designed for use in the M.2 connector. Next comes the marking “2280” indicating the physical size - 22 mm wide, 80 mm long. Not a word about thickness and single-sided or double-sided design. In this case, you will have to check from other sources or the drive manufacturer. After indicating the size marking it is written - SATA III. What does this mean? This means that the drive uses the SATA III logical interface. That is, we still have the same classic SATA drive, but made to fit the dimensions and M.2 connector. The speed advantages of PCI Express are not used here.

That's all, the seller's description is exhausted. What are we still missing? We lack an explicit indication of the type of connector key; let this remain on the conscience of the seller. But we visually see 2 slots, this means that this drive can be used as part of motherboards with a connector like B and type M. This is a visual assessment, I repeat again - you need to check with the manufacturer.

Let's try again:

SSD disk Samsung 960 EVO M.2 250 GB M.2 PCI-E TLC MZ-V6E250BW

Here we see the Samsung 960 EVO SSD, also on the M.2 connector. In general, without indicating the marking of physical dimensions and type, presumably also “2280” (always needs to be clarified from other sources). The following are PCI-E and TLC, what does this mean? This means that the device uses the PCI Express logical interface (which 2.0 or 3.0 is not clear, and how many 2x-4x lanes are also not known). TLC is a type of memory chip device. At this point, the online store considered the description sufficient. I think the warranty will tell him otherwise later...

But visually we see in this image one slot in the M.2 connector (presumably corresponding to the key M). And here you need to be careful, the device may physically fit into the connector B. And most likely, it will burn the board and the device. Therefore, it is necessary to know exactly what type of connector is installed on the board and which one is purchased.

Implementation of logical interface and command set.

For M.2 expansion cards, there are three options for implementing the logical interface and command set, similar to the SATA Express standard:

“Legacy SATA” Used for SSDs with a SATA interface, AHCI driver and speeds up to 6.0 Gb/s (SATA 3.0) “SATA Express” using AHCI Used for SSDs with a PCI Express interface and AHCI driver (for compatibility with a large number of operating systems) . Due to the use of AHCI, performance may be slightly less than optimal (obtained with NVMe), since AHCI was designed to interface with slower drives with slow sequential access (such as HDDs), rather than SSDs with fast random access. "SATA Express" using NVMe Used for SSDs with a PCI Express interface and a high-performance NVMe driver designed to work with fast flash drives. NVMe was designed to take advantage of the low latency and parallelism of PCI Express SSDs. NVMe makes better use of parallelism in the host computer and software, requires fewer data transfer stages, provides a deeper command queue, and more efficient interrupt handling.

What is NVMe?

NVM Express ( NVMe, NVMHCI - from English. Non-Volatile Memory Host Controller Interface Specification). The NVM Express logical interface was designed from the ground up with the main goals being low latency and efficient use of the high parallelism of solid-state drives through the use of a new instruction set and queuing engine optimized to work with modern multi-core processors.

The NVMe protocol speeds up I/O operations by eliminating the SAS (SCSI) command stack. NVMe SSDs connect directly to the PCIe bus. Applications receive dramatic performance gains from shifting I/O activity from SAS/SATA SSDs and HDDs to NVMe SSDs. Memory devices of the new type of storage are non-volatile and the latency when accessing them is significantly lower - at the level of latencies of RAM (volatile) memory.

The NVMe controller demonstrates all the advantages of an SSD: very low access latencies and a huge queue depth for read and write operations. The extremely low latency of storage devices significantly reduces the likelihood of data table locks during updates. This is critical for multi-user databases with complex and interconnected tables.

Very important: the motherboard's UEFI BIOS must contain an NVMe driver to boot the OS from the appropriate drive.

Pinout of typical M.2 connectors.

M.2 with Key B (1x SATA, 2x PCIe)

Pin Number	Pin Name	Description
1	CONFIG_3	Defines module type
2	3.3V	Supply pin, 3.3 V
3	GND	Ground
4	3.3V	Supply pin, 3.3 V
5	N/C
6-8	N/A
9	N/C
10	DAS/DSS
11	N/C
12-19	removed	Mechanical notch B
20	N/A
21	CONFIG_0	Defines module type
22-26	N/A
27	GND	Ground
28	N/A
29	PERn1	PCIe Lane 1 Rx
30	N/A
31	PERp1	PCIe Lane 1 Rx
32	N/A
33	GND	Ground
34	N/A
35	PETn1	PCIe Lane 1 Tx
36	N/A
37	PETp1	PCIe Lane 1 Tx
38	DEVSLP
39	GND	Ground
40	N/A
41	SATA-B+/PERn0
42	N/A
43	SATA-B-/PERp0	Host receiver differential signal pair. If in PCIe mode PCIe Lane 0 Rx
44	N/A
45	GND	Ground
46	N/A
47	SATA-A-/PETn0
48	N/A
49	SATA-A+/PETp0	Host transmitter differential signal pair. If in PCIe mode PCIe Lane 0 Tx
50	PERST#	PCIe reset
51	GND	Ground
52	CLKREQ#
53	REFCLKN
54	PEWAKE#
55	REFCLKP	PCIe Reference Clock signals (100 MHz)
56	MFG1
57	GND	Ground
58	MFG2	Manufacturing pin. Use determined by vendor.
59-66	removed	Mechanical notch M
67	N/A
68	SUSCLK
69	CONFIG_1	Defines module type
70	3.3V	Supply pin, 3.3 V
71	GND	Ground
72	3.3V	Supply pin, 3.3 V
73	GND	Ground
74	3.3V	Supply pin, 3.3 V
75	CONFIG_2	Defines module type

M.2 with M key (1x SATA, 1x, 2x, or 4x PCIe)

Pin Number	Pin Name	Description
1	CONFIG_3	Defines module type
2	3.3V	Supply pin, 3.3 V
3	GND	Ground
4	3.3V	Supply pin, 3.3 V
5	PERn3	PCIe Lane 3 Rx
6	N/A
7	PERp3	PCIe Lane 3 Rx
8	N/A
9	GND	Ground
10	DAS/DSS	Device Activity Signal / Disable Staggered Spinup
11	PETn3	PCIe Lane 3 Tx
12	3.3V	Supply pin, 3.3 V
13	PETp3	PCIe Lane 3 Tx
14	3.3V	Supply pin, 3.3 V
15	GND	Ground
16	3.3V	Supply pin, 3.3 V
17	PERn2	PCIe Lane 2 Rx
18	3.3V	Supply pin, 3.3 V
19	PERp2	PCIe Lane 2 Rx
20	N/A
21	CONFIG_0	Defines module type
22	N/A
23	PETn2	PCIe Lane 2 Tx
24	N/A
25	PETp2	PCIe Lane 2 Tx
26	N/A
27	GND	Ground
28	N/A
29	PERn1	PCIe Lane 1 Rx
30	N/A
31	PERp1	PCIe Lane 1 Rx
32	N/A
33	GND	Ground
34	N/A
35	PETn1	PCIe Lane 1 Tx
36	N/A
37	PETp1	PCIe Lane 1 Tx
38	DEVSLP	Device Sleep, input. If driven high the host is informing the SSD to enter a low power state.
39	GND	Ground
40	N/A
41	SATA-B+/PERn0	Host receiver differential signal pair. If in PCIe mode PCIe Lane 0 Rx
42	N/A
43	SATA-B-/PERp0	Host receiver differential signal pair. If in PCIe mode PCIe Lane 0 Rx
44	N/A
45	GND	Ground
46	N/A
47	SATA-A-/PETn0	Host transmitter differential signal pair. If in PCIe mode PCIe Lane 0 Tx
48	N/A
49	SATA-A+/PETp0	Host transmitter differential signal pair. If in PCIe mode PCIe Lane 0 Tx
50	PERST#	PCIe reset
51	GND	Ground
52	CLKREQ#	Reference clock request signal
53	REFCLKN	PCIe Reference Clock signals (100 MHz)
54	PEWAKE#	PCIe WAKE# Open Drain with pull up on platform. Active Low.
55	REFCLKP	PCIe Reference Clock signals (100 MHz)
56	MFG1	Manufacturing pin. Use determined by vendor.
57	GND	Ground
58	MFG2	Manufacturing pin. Use determined by vendor.
59-66	removed	Mechanical notch M
67	N/A
68	SUSCLK	32.768 kHz clock supply provided by the Platform chipset
69	CONFIG_1	Defines module type
70	3.3V	Supply pin, 3.3 V
71	GND	Ground
72	3.3V	Supply pin, 3.3 V
73	GND	Ground
74	3.3V	Supply pin, 3.3 V
75	CONFIG_2	Defines module type

M.2 with key A (PCIe ×2, USB 2.0, I2C and DP ×4) and E (PCIe ×2, USB 2.0, I2C, SDIO, UART and PCM).

Pin id.	Pin name	Description
		Ground
	3.3V	3.3V power supply
	USB_D+	USB high-, full-, and low-speed data pair positive
	3.3V	3.3V power supply
	USB_D-	USB high-, full-, and low-speed data pair negative
	LED1#
		Ground
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Substrate removed to act as physical key
	LED2#
		Don't connect
		Ground
		Don't connect
		Don't connect
		Don't connect
		Don't connect
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Substrate removed to act as physical key
		Don't connect
		Ground
		Don't connect
	PETp0	PCI Express lane 0 module transmitter pair positive
		Don't connect
	PETn0	PCI Express lane 0 module transmitter pair negative
	Vendor defined
		Ground
	Vendor defined
	PERp0	PCI Express lane 0 module receiver pair positive
	Vendor defined
	PERn0	PCI Express lane 0 module receiver pair negative
	COEX3	Antenna coexistence signal 3
		Ground
	COEX2	Antenna coexistence signal 2
	PEFCLKP0	PCI Express reference clock pair positive
	COEX1	Antenna coexistence signal 1
	PEFCLKN0	PCI Express reference clock pair negative
	SUSCLK	32.768 kHz clock module input
		Ground
	PERST0#	PCI Express reset
	CLKREQ0#	PCI Express clock request
	W_DISABLE2#	Wireless disable 2
	PEWake0#	PCI Express wake
	W_DISABLE1#	Wireless disable 1
		Ground
	SMB_DATA	SMBus data signal
	Reserved
	SMB_CLK	SMBus clock signal
	Reserved
	ALERT#	SMBus alert signal
		Ground
	Reserved
	Reserved
	UIM_SWP
	Reserved
	UIM_POWER_SNK
		Ground
	UIM_POWER_SRC
	Reserved
	3.3V	3.3V power supply
	Reserved
	3.3V	3.3V power supply
		Ground

Conclusion.

In conclusion, the advantages adopted by the SATA 3.2 standard become obvious. The emergence of new specifications and connectors will expand the choice of compatible expansion cards for both laptops and desktop computers. It will also increase the overall performance of computing systems from laptop to server.

The interface itself is fraught with a large number of pitfalls for both the average user and the professional. Perhaps this is due to its novelty, or maybe some “dampness”.

In any case, I tried to collect as much important information as possible. Any questions you may have can be asked in the comments to the article. If the article helped you, you can thank me by sending donations to a Yandex wallet, the form for sending money is located at the very bottom of the site (footer). Thank you for your attention to my article.