Solid state drives (SSDs) are the top technology in storage right now, combining the best of speed, reliability and form factor. IT managers may be looking to upgrade older systems with hard drives to SSD, or older SSDs to newer, faster or higher capacity SSDs. Since SSDs are now in their fourth generation, everything about these types of drives have greatly improved.

In making the decision to upgrade, the form factor — the shape and size of the SSD — can make a huge difference in compatibility, capability and cost. Let’s take a look at the four primary options available: 2.5-inch SATA SSDs, 2.5-inch NVMe SSDs, M.2 SATA SSDs and M.2 NVMe SSDs.

Why form factor matters

The choice of SSD is generally guided by the interfaces available in the system, whether they are laptops, tablets, PCs or servers. The first step is to determine what types of storage connections exist and what other options might be available, such as open PCIe slots that can take PCIe storage adapters to allow the use of newer, faster drives.

2.5-inch SATA SSDs

Many SSDs are currently made in 2.5-inch form factors, which is fairly common in laptops, servers and other computing devices.

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The 2.5-inch SATA SSD comes with improved speed over the original 100 MB/s, now up to 560 MB/s or better — typically to the maximum that the SATA interface will allow. The longevity of the drives is far greater than that of the first generation SSDs, which may only last a year or two. Typical 2.5-inch SSDs include the Samsung 883 DCT and the Samsung 870 QVO.

However, if you aren’t forced into the 2.5-inch form factor, there are other criteria to consider.

2.5-inch NVMe SSDs

The 2.5-inch NVMe SSD adopts a U.2 interface that gives it the ability to go faster than the SATA bus can support. By using the newer 1.3a or 1.4 NVMe standard, drives can sustain throughputs as high as 3,500 MB/s, compared to the 550-600 MB/s that the SATA bus supports. Input/output operations per second (IOps) are also as much as 10 times higher, going from around 50,000 IOps in a SATA drive to as many as 500,000 IOps with NVMe.

A typical 2.5-inch NVMe SSD is the Samsung 983 DCT, which looks like a 2.5-inch SATA SSD but operates with an NVMe interface and performance.


The newer M.2 form factor is more compact than the 2.5-inch SSD and offers a choice of SATA or NVMe interface. M.2 drives are 22mm wide and may be 30mm, 42mm, 60mm, 80mm or 110mm long. M.2 SATA SSDs, like the Samsung 860 EVO M.2 SATA, offer the smaller form factor that goes with M.2, but with the less expensive SATA interface. This makes it ideal for applications where the highest level of performance is not necessary.


The latest type of SSD available is the M.2 NVMe SSD. Combining the faster NVMe interface with the compact M.2 form factor, it offers high levels of performance with up to 3,500 MB/s throughput and up to 400,000 IOps. It also offers lower power consumption and more efficient power usage than the 2.5-inch NVMe. The Samsung 983 DCT is available in the M.2 format in addition to the 2.5-inch form factor.

Which one is right for your device?

When you’re buying your next SSD, keep the device you’re seeking to upgrade in mind, whether it’s a laptop, desktop or server. Here’s a breakdown on how to evaluate for each.

Laptops: You may have a space for one, two or four 2.5-inch SATA drives, or for two M.2 slots and one 2.5-inch SATA drive. Keep in mind that laptops with M.2 slots may have one or two that are either SATA or NVMe slots. To upgrade with new drives, it’s important to know what type of slots the laptop has as this will determine which SSD drives fit. Almost all laptops with a traditional hard drive (those that are most in need of upgrading) will be of the 2.5-inch SATA variety.

Desktops: Over the last five years, many motherboards have begun supporting NVMe slots and “sleds” — PCIe cards that can hold as many as four M.2 NVMe SSDs. While there are many applications that won’t see much improvement going from SATA to NVMe, games, graphics creation programs, 4K video editing, data mining and other specialized apps can take advantage of the 6x performance gains offered by the best NVMe drives.

On the other hand, many desktop systems come with 3.5-inch hard drives. If you’re interested in replacing these with SSDs, there are inexpensive adapters that allow you to mount a 2.5-inch drive in a 3.5-inch bay. The interfaces are the same for both: any SATA SSD should be able to use the same cable that was originally plugged into a 3.5-inch SATA hard drive. Any system with a free 4x PCIe slot can use a sled and one or more PCIe SSDs, though older motherboards that don’t support PCIe 3.0 or greater may not work well with sleds. Even if they do, their older backplanes may not support the full speeds necessary to get the most out of the newer NVMe SSDs.

Servers: Newer models are now being designed with 2.5-inch SSDs and NVMe SSDs in mind. They can support 20 2.5-inch NVMe drives or as many as 36 M.2 SSDs. Upgrading older systems with new drives requires the same investigation as with laptops or PCs. Determine what types of interfaces the existing drives use and replace them with SSD models that use the same interface.

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Jonathan Hassell

Jonathan Hassell is an award-winning writer specializing in enterprise information technology, including administration, security, and mobile. His work has appeared in Computerworld,, Network World, and dozens of other publications.

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