SSD interface types their connectors and forms factors

Hello friends. In this article, we will look at such a question: SSD interface types. Solid state drives are a new form of computer hard drive that drives the final nails into the coffin of an old HDD format hard drive. The development of the SSD market has given rise to a lot of specifics of this device, and among these specifics is the connection interface. Initially, it is not difficult with it: for internal drives, it can be SATA and PCI-E. But the SSD interface is often used in a broad sense, which also includes such device specifics as the connection connector and form factor. 

ssd interface types

Let’s figure it out thoroughly: what is an interface, what is a connection connector, what is an SSD form factor. And let’s see what interfaces, connectors, and form factors exist for SSDs in today’s market for these devices.

SSD interface types: SSD interface

An SSD interface is a logical interface for connecting it to a computer in the context of a mechanism for exchanging data with computer devices. Internal SSDs are connected to the computer via SATA, PCI-E, SAS interfaces. External devices – via USB and Thunderbolt interfaces.


sata ssd
sata ssd

Working with SATA, all SSDs only use its latest generation SATA III with up to 600MB / s bandwidth. But they can support different revisions of SATA III – SATA Revision 3.0, 3.1, 3.2. Each newer revision slightly improves the performance of the SSD. By the way, you can find out the SATA revision using the Smarthdd program.

But in any case, all SSDs are compatible with previous generations of SATA, and they will work on computers where motherboards support, for example, only SATA II. But, of course, they will work within the bandwidth of up to 300 Mb / s. A typical SATA SSD comes in a 2.5 ”form factor. These SSDs were the first to appear. And such a drive can be installed in any PC or laptop. 

SATA SSDs also come in mSATA and M.2 form factors. SATA drives work with the old AHCI data transfer protocol.


Later, SSDs with PCI-E interface appeared a faster interface providing, accordingly, a higher data transfer rate. Different SSDs support different generations of this interface – PCI-E 3.0 and PCI-E 4.0. The PCI-E 3.0 interface can be with two data lines – PCI-E 3.0 2x, this provides a speed of slightly less than 2 Gb / s. But the PCI-E 3.0 interface can be with four data lines – PCI-E 3.0 4x, and then it can provide a maximum speed of 3.9 Gb / s. PCI-E 4.0 interface provides 4 data lines – PCI-E 4.0 4x, and it can provide a maximum speed of 7.88Gb / s. PCI-E SSDs work through M.2 and U.2 slots. All modern high-speed PCI-E drives support NVMe technology, the fastest data transfer protocol. But some older PCI-E drives (usually PCI-E 2.


SAS is both an interface and a connector for connecting internal server-class drives, we will talk about it later.

USB and Thunderbolt

USB and Thunderbolt are both interfaces and connectors for connecting external SSDs, we will also talk about them in more detail later.

SSD interface types: SSD connectors

ssd connectors
ssd connectors

A connection connector is a type of hardware connection of an SSD through a specific interface, it is a physical interface.


The lion’s share of the market for internal solid-state drives is occupied by those with both the SATA interface and the SATA connector, to be precise, with the SATA III connector. This is the aforementioned typical SATA SSD in the 2.5 ”form factor, which can be installed in any computer by connecting to the SATA III port (if not, then to the SATA II port) on the motherboard of a PC or laptop.


While SATA is both a connection interface and a hardware connector for connecting an SSD itself, M.2 is not an interface, but a hardware connection connector and a form factor. SATA and PCI-E SSDs can be connected via the M.2 slot. And so that we can connect an SSD with the desired interface to the computer, the motherboard of the PC or laptop must have an appropriate M.2 slot. The M.2 slot on some motherboards of PCs and laptops can accept either the SATA bus or the PCI-E bus, i.e. such devices have either M.2 SATA or M.2 PCI-E slot. Laptops usually, if they have an M.2 slot, it is either an M.2 SATA slot or an M.2 PCI-E slot. But on separate PC motherboards, M.2 slots can work in both modes – both in M.2 SATA mode and in M.2 PCI-E mode. And, accordingly, you can connect either M.2 SATA drives or M.2 PCI-E drives to such motherboards.

But the M.2 slot on the motherboard or laptop still has different keys, which determine the structural differences of the slot:

  • Key B supports PCI-E x2 and SATA III;
  • M key supports PCI-E x4 and SATA III;
  • the B + M key supports all interfaces, respectively.   

The M.2 slot keys on the motherboard and laptop must match the keys on the SSD. Also, the M.2 slot and the M.2 drive must be the same size. An M.2 slot (or even several) for connecting M.2 drives is provided today by almost all modern motherboards for PCs and laptops. Installing an M.2 drive into your PC’s motherboard is very easy. As well as simply installing it in a laptop.

When buying a drive with an M.2 connection, it is important to understand very accurately what kind of slot we have on the motherboard of a PC or laptop – what interface it is for, what key it has, and what sizes of drives it supports. We carefully study our motherboard PC or laptop, use their specifications on the official website, use device instructions.

Older computers and relatively so (even generations of DDR4 RAM released earlier than 2015) do not have an M.2 PCI-E slot for installing high-speed PCI-E NVMe drives. Installing such a high-speed SSD on an old PC can only be done with a special PCI-EM adapter. 2.

But in order to boot Windows from such a drive, you need to modify the computer BIOS to support NVMe, and this is possible not for every motherboard. And, of course, the modification process itself carries risks.


mSATA (mini-SATA) is both a form factor and a connector for connecting small drives in laptops, and, accordingly, laptops in their design must provide for an mSATA slot. To the naked eye, an mSATA drive can be confused with an M.2 drive.

The mSATA connector on laptops is now virtually ousted from the market by the M.2 connector. And there are very few mSATA drives themselves on the market.

USB and Thunderbolt

USB and Thunderbolt are both interfaces and connectors for connecting external SSDs. Depending on the generations of interfaces, their connectors have structural differences, but these connectors are compatible with connectors of previous generations of interfaces. External USB-SSDs are now available with connectors:

  • USB 3.2 gen1, providing data transfer rates up to 600 Mb / s;
  • USB 3.2 gen2 supporting data transfer rates up to 1250 Mb / s.

But, of course, if we connect such a drive to the usual USB 3.0 or even 2.0 ports on a computer, then there will be no sense from the interface generation implemented in the drive itself, data transfer will be limited to USB ports on the computer. There is a USB-SSD with a USB C connector (aka USB Type-C, slightly larger than microUSB), and there are different generations of this type of connector interface – USB C 3.2 gen1 and USB C 3.2 gen2.

External drives with a Thunderbolt interface and connector in its version 3 can work at the level of high-speed internal SSD PCI-E M.2. Drives with the implementation of Thunderbolt v3 can read data at speeds up to 2800 MB / s, write at speeds up to 2100 MB / s. External drives with Thunderbolt in its version 2 can read and write data at speeds up to 950 MB / s. These SSDs support NVMe. But Thunderbolt is implemented primarily on Apple computers.

There are high-speed external drives with Thunderbolt interface, but with a USB C connector, i.e. connected, respectively, via USB. However, to connect such a drive to a computer, it must support Thunderbolt mode.


U.2 is a state-of-the-art, hot-swappable, high-priced, server-class internal hard drive connector. Works through PCI-E interface, providing high data transfer rates, most of these drives support NVMe. For an SSD with a U.2 connector to work, it must be provided by the computer’s motherboard. 


SAS is an old interface and connector for connecting internal server class drives, has a modern implementation with a bandwidth of up to 2.8 Gb / s. SAS drives can also be connected to a computer if its motherboard provides such a connector.

SSD interface types: SSD Form Factor

An SSD form factor is the physical form of a device. The form factor characterizes the shape and dimensions of the SSD, the hardware connector, in some cases, determines the presence of a “seat” in the PC system unit or laptop design.

2.5 “

2.5 ”is a popular form factor for internal SSDs. It comes from the 2.5 “HDD form factor for laptops, i.e. a hard drive in a compact form that can be installed both in the PC system unit and in the laptop case. The 2.5 ”form factor uses internal SATA, SAS and U.2 drives, as well as external SSDs. An internal drive with this form factor can be attached to the walls of a PC case.

Can be placed in sleds and in a common PC hard drive rack.

Or you can even just attach it with two bolts on one side, and nothing happens to the drive.


M.2 is both a connector and a form factor for internal SSDs. And, accordingly, M.2 is the form factor for the M.2 slot. As mentioned, it has different keys and sizes, which should be compatible with the design of the M.2 slot on the PC motherboard or laptop.


mSATA is the form factor for the mSATA connector.