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Solid state drives (SSD) have become more widely used than hard disk drives (HDD) due to increased read and write speeds and fewer moving parts. You may have noticed that SSDs come in different types and form factors, so distinguishing between them can be a little confusing. SSDs have different connectors, connection protocols, technologies, and form factors. The basic SSDs are 2.5″ SATA, M.2 SATA, M.2 NVMe, NVMe PCIe, and U.2 (formerly SFF-8639), each of which has its advantages and disadvantages.

2.5″ SATA

• Interface: SATA
• Connection protocol: SATA
• Technology: SATA
• Form factor: 2.5 inches

Description: 2.5 inch SSD is the traditional form of memory that most of us are familiar with in old computers. This memory is usually installed on the SSD tray in the personal computer case. 2.5-inch SSDs are connected to the motherboard through the SATA protocol, and their maximum transfer speed is around 500 to 600 MB/s. SSDs that use NVMe technology have much higher bandwidth, and their maximum transfer speed until the time of writing this article is about 7000 to 7500 MB/s, which is almost 12 times faster!

Remember that there are also 3.5-inch form factors, But they are too expensive for ordinary consumers.

Pros: 2.5″ SATA memory is cheaper, easier to access, and works on almost any motherboard. While it’s not as fast as NVMe SSDs, it’s still much faster than hard drives (which have transfer speeds of around 160MB/s) and can handle most tasks just fine. 2.5-inch SATA drives also have the advantage of no moving parts, breaking less than hard disks.

2.5-inch drives are easier to remove and replace than M.2 drives because they are separate from the motherboard. If you’re upgrading your current hardware, you don’t need to replace your current graphics card or other components.

Disadvantages: Compared to NVMe, 2.5-inch SSDs have a really low transfer speed due to the limitation of the SATA connection protocol and are bulkier than the M.2 form factor. 2.5-inch SSD drives require both a SATA data cable and a SATA power cable, which can create a mess in the appearance of the cables.

M.2 SATA

Quick specs

• Interface: M.2
• Connection protocol: SATA
• Technology: SATA
• Invoice form: M.2

Description: The second generation of mini SATA and the highly used SSD form factor are of the same type and available in different sizes. Their width is 22 or 30 mm, and their length varies from 16 mm to 110 mm (in 2022). You can see these memories as 2280, 1630, 3030, etc., where the first two digits indicate the width and the last two or three digits indicate the length of the device.

M.2 SATA SSDs have two U-shaped cutouts or “keys” near the edges, also known as “M” and “B” keys. On the other hand, most M.2 NVMe SSDs only have an “M” key. However, there are exceptions, so keep this in mind when purchasing any memory.

SATA bandwidth is lower than NVMe, but if you have an older motherboard, it may not support NVMe or PCIe bandwidth. Other motherboards are equipped with a dedicated M.2 slot, so there is no need to use the SATA slot. Most of the time, M.2 slots support M.2 SATA and M.2 NVMe SSDs. Be sure to check what SSD technology your motherboard supports.

Pros: Data transfer speed is much faster compared to 2.5-inch SSDs. It can be installed on any motherboard that supports the M.2 interface, which is very common among motherboards. SATA M.2 drives are smaller than 2.5-inch drives and about the thickness of a piece of gum. Since they connect directly to the motherboard, it saves space in the case because you don’t need SATA cables.

Cons: M.2 SATA SSDs are slower than NVMe, and while most modern motherboards support M.2 connectors, not all do. The transfer speed of M.2 SATA SSDs are limited by the connection protocol of their 2.5-inch SATA cousins. They are slightly more expensive than today’s 2.5-inch SATA SSDs.

Additionally, installing or replacing M.2 is a hassle because it requires direct access to the motherboard and may require replacing the entire motherboard or even removing other components.

M.2 NVMe

Quick specs

• Interface: M.2
• Connection protocol: PCIe
• Technology: NVMe
• Invoice form: M.2

Description: NVMe stands for Non-volatile Memory Express, known for its high bandwidth and fast transfer speed. Non-volatile or non-volatile memory indicates that no electricity is needed to maintain the stored information of this device.

In contrast to RAM or DRAM, the storage memory is “volatile”; that’s why the data is lost after the power is turned off.

The read or write speeds of the best NVMe SSDs on the market can exceed 3,000 MB/s (3 GB/s), with some NVMe PCIe Gen 4 SSDs capable of 7,500 MB/s. Top SATA SSDs run at around 550MB/s, so NVMe SSDs have the fastest transfer speeds on the market.

You may hear the term “Lane” when buying M.2 NVMe SSDs. More path equals longer SSD and faster transfer speed. Each way represents about 1GB of transfer speed. A 4-lane NVMe SSD has twice the bandwidth of a 2-lane NVMe SSD. Most 4-way M.2 NVMe SSDs have one key, unlike M.2 SATA SSDs with two keys.

However, some two-way M.2 NVMe SSDs, like M.2 SATA, have two keys. Be sure to read the product description carefully before buying because this can cause you trouble when connecting the SSD to the motherboard. Also, check transfer speeds; if speeds exceed 550MB/s, look for an M.2 NVMe SSD, not an M.2 SATA.

Pros: M.2 NVMe SSDs have high transfer speeds. Due to the M.2 form factor, these memories are smaller than the 2.5-inch SATA SSD.

According to the PCIe connection protocol, M.2 NVMe SSDs are backward and forwards compatible, so that we can use PCIe 3.0 NVMe SSDs with a PCIe 2.0 system or vice versa. However, using a PCIe 3.0 SSD with a PCIe 2.0 motherboard will reduce overall bandwidth availability. On the other hand, using a PCIe 2.0 SSD with a PCIe 3.0 motherboard will cause performance hiccups.

Cons: The faster the drive, the more expensive it is. M.2 NVMe drives cost more than 2.5-inch SSDs or M.2 SATA. Also, while motherboards may be compatible with the M.2 form factor, they may not support NVMe. Therefore, before buying, read the specifications of your desired motherboard carefully.

M.2 NVMe SSDs are also reportedly great because they quickly transfer a lot of data. If your computer does not have a solid cooling solution, installing or upgrading a cooler is better before installing M.2 NVMe SSDs.

Of course, not all systems need this kind of speed! If you are not a professional gamer, you need to use powerful graphics equipment and wait for your computer to upgrade; you can save a little with a SATA SSD and install it more easily if you plan to upgrade the current system.

NVMe PCIe (AIC)

Quick specs

• Interface: PCIe
• Connection protocol: PCIe
• Technology: NVMe
• Form factor: PCIe (expandable card)

Description: These SSDs are comparable to M.2 NVMe in many ways, including their fast transfer speed. The only difference is how they are connected to the motherboard; they use the PCIe slot instead of the M.2 connector. They are much more expensive on average than the M.2 NVMe form factor.

Pros: If your motherboard doesn’t support M.2, almost every modern desktop motherboard supports PCIe. You’ll get fast NVMe transfer speeds without needing an M.2 connector, which is great for upgrading older systems. Due to the increased surface area, NVMe PCIe SSDs run cooler than smaller M.2 NVMe SSDs, so overheating is not a factor.

Cons: These drives are much larger than M.2 drives and take up one of your PCIe slots. It may not be easy to install on your existing equipment if you already have a graphics card or other components connected to the motherboard. They are also very expensive because they usually have a high capacity and are used in enterprise storage systems.

SSD U.2

Quick specs

• Interface: U.2 (SFF-8639)
• Connection protocol: PCIe/SAS/SATA
• Technology: NVMe
• Form factor: 2.5″

Description: U.2 SSD is unusual in consumer applications and is created for relatively specific use cases. With PCIe AIC SSD drives, users must open a server before inserting or removing them. On the other hand, U.2 SSDs can connect hot or hot plugs, which means they can be connected with or without prior notice, like SATA SSD drives or standard hard disks.

You’ll find U.2 SSDs more often in servers and enterprise storage devices, as they have more capacity than most M.2 SSDs and better heat dissipation due to their increased surface area. They are compatible with 2.5″ and 3.5″ PCIe slots.

Pros: These drives are hot-swappable, making it easy for administrators to upgrade system memory. They are compatible with HDDs and can use a variety of connection protocols, depending on the system’s back panel. Additionally, they can operate at NVMe transfer speeds without being as hot as M.2 due to the increased surface area and ability to dissipate heat.

Disadvantages: U.2 SSDs are too expensive due to the SFF-8639 connector. For this reason, some legacy enterprise storage infrastructures cannot accommodate SFF-8639 connectors.