M.2 vs PCIE – Complete Comparison

Last Updated on November 6, 2020

M.2 SSDs (Pronounced M-dot-two) are small form factor SSD options that were developed for small form factor devices like laptops and notebooks. Over the years, these drives have found themselves in use in desktop motherboards that have the supporting slot.

PCIe (Peripheral Component Interconnect express) on the other hand is a standard that is developed by a consortium of industry leaders known as the PCI Special Interest Group or PCI-SIG for short.

It was initially developed as a means to allow the addition of peripheral components to a motherboard through the use of a standard connector. Eventually, storage devices joined the ranks of devices connecting to the motherboard over the PCIe bus.

Here we look at M.2 Vs PCIe and find out which kind of SSDs they support. To set us off, an M.2 interface can support several connection protocols including PCIe.


What is M.2?

An SSD that fits into the M.2 Slot. Source: microcontrollertips.com

Solid State Drives are mass storage media devices that are used to store data. For those that are used internally in a computer, they serve as the storage for the computer’s data and programs and since they are non-volatile, they don’t require any power to persist information.

They are a form of flash memory storage and hence, you don’t get any moving parts like on a regular hard drive. Instead, semiconductors are used to store the data.

Now, M.2 does not only refer to the form factor of the SSD and also the size of the slot that the M.2 SSD fits into, it is also the name of an interface standard. What this means is that besides SSDs, an M.2 interface can also be used for other devices like Wi-Fi and USB expansion.

Also Read: How Many PCIe Lanes Does M.2 Slot Use?

M.2 SSDs

SSD Key Type
SSD Key Type – Source: atpinc.com

M.2 SSDs follow can be both SATA or PCIe based. The PCIe SSDs are called NVMe SSDs.

Also Read: NVME vs SATA vs mSATA SSD

SSDs that utilize the M.2 interface standard come in various form factors. You may have seen a peculiar 4 or 5-digit number used to refer to the size of the SSD. A good example is the 2260 model.

The size of the device can be inferred from this number where the first two digits correspond to the drive’s width and the remaining numbers correspond to the length of the device. Hence, the 2260 drive measures 22 mm by 60 mm.

You must pay attention to this number before you go ahead and purchase a drive. You may get one that doesn’t fit your M.2 slot.

The length is also crucial because some motherboards do not support some very long drives.

Besides the size of the drives, the devices can also come in a single-sided or double-sided form factor.

Also Read: PCIe 3.0 vs 2.0

What is PCIe?

PCIe is a connection standard that has been in use ever since it replaced the much older PCI standard. Although both PCI and PCIe can still be found in use in some newer boards, the latter has taken off as the go-to implementation where speed and bandwidth are desirable.

What makes the PCIe connection so special is its serial transfer. Instead of data being pushed to and from the CPU through a common connection, each slot has lanes that are used individually. This means that with more lanes you get more data transferred at a given time.

PCIe is available in X1, X4, X8, and X16 flavors, though the X4 is the most commonly used one with SSDs.

PCIe Slots on a motherboard.
With PCIe slots, users can add supported components to a computer. This includes adapters for storage devices like SSDs. Source: ccboot.com


Several kinds of SSDs make use of the serial bus. They come in different form factors and offer a wide range of features.

For starters, you need to know that an M.2 NVMe also uses PCIe lanes. However, sometime when we talk about PCIe SSD, we may refer to the add in card SSD.

Plug-in PCIe SSDs get plugged straight into a PCIe slot and unless you run into some issues and need to do some configurations in the BIOS, they usually work right away.

PCie Slot ssd
These are rarely found on personal PC. They are super fast and are found in workstation PCs.

On the other hand, smaller M.2 NVME SSDs have a low physical profile meaning you can install them in small spaces utilizing the M.2 slot. A laptop is a great example.

With a PCIe 3.0 card and slot operating at the X4 configuration, a user is presented with a maximum theoretical transfer speed of up to 4GB/s, although real-world tasks may not see this kind of performance.

Nevertheless, it’s good to know that the feature is there if you’ll end up needing it.

Note that both M.2 NVMe SSD and a x4 PCIe Add in SSD as shown above, both use 4 PCIe lanes and hence have the same maximum transfer speed.

Also Read: What are PCIe Lanes?

M.2 PCIe vs M.2 SATA SSD

SATA SSDs are quite different from M.2 SSDs in that they use a different connection interface.

A SATA slot is the L-shaped connector on your motherboard. It has been used for many years as a standard to connect devices like SSDs and Hard drives to the motherboard.

With the release of SATA III, the connection saw some performance upgrades but still, SATA SSDs do not perform as well as M.2 PCIe SSDs.

SATA Interface has a transfer speed capped at 6 Gigabits per second which translates to about 600 MB/s. In the real world, SATA SSDs usually hit up to 550 MB/s. However, a PCIe SSD is capable of much more speed than that.

Also, SATA SSDs are more prevalent than M.2 PCIe SSDs because the SATA interface is common on almost all modern motherboards. So, manufacturers tend to develop devices that have a market.

SATA SSDs are larger in profile than M.2 SSDs. With the average SATA SSD measuring about 2.5 inches whereas M.2s come up at a few dozen millimeters.

SATA SSDs are relatively more affordable than most other kinds of PCIe SSDs. Source: digitaltrends.com

Mini PCIe vs M.2

A Mini PCIe card (mPCIe) uses the same PCIe bus used by full-size PCIe cards with the added benefit that its size, as well as its connector, are smaller in size.

Because laptops are not large enough for full-sized PCIe slots, mPCIe was the next best solution. An SSD that makes use of the mPCIe interface on a motherboard can leverage the speeds that the PCIe bus allows. With this, users get fast-performing laptops.

M.2 SSDs are much smaller than mPCIe drives. For this reason, M.2 drives are the most sought-after alternative for mobile computing devices.

Additionally, the M.2 standard has been around for much longer than the mPCIe. MPCIe was developed long after the regular PCIe interface. Because of their long-term use, M.2 is great for laptops as well as other devices due to the support that it has.

Also Read: 5 Best Motherboards for Photo Editing in 2021

M.2 vs PCIe

When it comes down to the two, users will have to decide exactly what they are going for because each of these drives fits a very particular use case.

If you are someone who likes to use their desktop and you appreciate high speeds during data transfers as well as great boot times, then the PCIe option will be great.

An M.2 Drive exhibits very high speeds and you can get some high capacity drives that suit your needs.

On the other hand, laptop or mobile computer users will need something more compact but still performs very well. For such users, it’d be best to go for a device with an M.2 interface where you can plug your SSD.

M.2 vs PCIE
SSDs come in different shapes and sizes depending on the motherboard and the connector they use. Source: tomshardware.com


Have you ever been confused about those small SSDs that are only a little larger than a credit card? If so, other devices look pretty similar but are different.

Here we look at M.2 vs PCIe, two standards that offer an interface for connecting several components to your motherboard. Among these are SSDs, some of the fastest flash storage you can get in the market.

SSDs built for either of these interfaces will work fine with computers that they support, however, the best one to choose will depend on a user’s needs since they have their use case.


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