What Is The Difference: M.2 SATA SSD Vs. M.2 PCI Express (PCIe) SSD

By Tim K
What Is The Difference: M.2 SATA SSD Vs. M.2 PCI Express (PCIe) SSD

You may have noticed that the M.2 SSD phrase has been mentioned many times in previous articles, but I didn't have much time and an appropriate situation to explain more. Therefore, today, I would like to explain more about the M.2 interface, M.2 cards, M.2 solid-state drives.

Furthermore, I will point out the differences between M.2 SATA SSD, M.2 PCI Express SSD (PCIe), and M.2 NVMe SSD. Perhaps this is the thing that confuses you the most and can't make the right choice when buying an SSD.

So are you ready to learn about M.2?

What Is M.2?

Firstly, M.2, previously known as NGFF (stands for Next Generation Form Factor), is a specification of computer expansion cards and associated connectors that are internally mounted. It's a true successor to mSATA that uses Mini PCI Express (also known as Mini PCIe, Mini PCI-E, or mPCIe) physical card design and connectors.

The M.2 platform supports a wide range of M.2 cards and can be set up with various hardware and functionality to fit the specific needs of each system and give a variety of configuration options for consumers.

For instance, M.2 cards may comprise:

  • Wi-Fi, Bluetooth, Cellular, NFC cards.
  • SATA SSDs (Use SATA Bus via M.2 connector).
  • PCIe SSDs (Use PCI Express Bus via M.2 connector).

Although the appearance is the simplest observable way to recognize the difference between the M.2 cards, this standard also uses a numerical naming convention to classify the dimension, particular characteristic, and functionality of the card. For example, 1630, 2230, 2242, 2260, 2280, 22110 or 3030. The first two digits (e.g., 22mm) define the width while the last two or three digits (e.g., 80mm) define the length of the M.2 card. The most popular supported form-factors are 2242 and 2280.

M.2 SSD 2230, 2242, 2260, 2280, and 22110 form factor
Image Caption: The difference between M.2 2230, 2242, 2260, 2280, and 22110 form factor in size.

Besides, the connector keying notches can be used to distinguish the different purposes and functionalities of both M.2 hosts and devices. The unique key notches of M.2 modules also prevent them from being attached to mismatched host connectors. Modules with one notch can only be used for one particular type of host connector, whereas modules with two notches can be used in two different types of host connectors.

What Is M.2 SSD?

An M.2 SSD is a solid-state drive that is designed to fit the specifications of the M.2 interface. It has many different sizes and keying notches to suit each type of device. For example, if your laptop has an M.2 port that supports modules with the keying notch type M and the length is up to 60-mm, then you can't attach an SSD with the keying notch type B, or the length is 80-mm. That is why you need to double-check what kind of M.2 SSD your computer supports before purchasing.

The Difference: M.2 SATA SSD Vs. M.2 PCI Express (PCIe) SSD

In which case should you use M.2 SATA SSD or M.2 PCIe SSD? What is the difference between them? Basically, they use two different interfaces with different speeds. M.2 PCIe SSD is much faster than M.2 SATA SSD, but the price is much higher.

Let me explain a bit deeper regarding M.2 SATA SSD and M.2 PCIe SSD!

M.2 SATA SSD

M.2 SATA SSD

The SATA revision 1.0 (also known as SATA I, SATA 1.5Gb/s) was released in early 2003, and since then, it has consolidated its position as one of the most widely used transfer interfaces nowadays. The latest generation is SATA III, formally known as SATA 6Gb/s. It runs at 6Gb/s and is capped at a maximum transfer speed of up to 600MB/s.

Although the SATA interface is quite ubiquitous and most widely used, most reputations belong to the 2.5-inch hard drive form factor. M.2 SATA SSDs aren't actually the more popular selection as there's no improvement in the transfer speed compared to the traditional SATA form factor. That's why many people often reserve the M.2 slot for other purposes than using an M.2 SATA SSD.

M.2 PCIe SSD

M.2 PCIe SSD PCI Express

In theory, an M.2 PCIe SSD is more like a SATA SSD on a supercar. While the SATA interface is capped at 6Gb/s, PCIe 3.0 has 32GB/s of the bandwidth throughput, which is a lot faster. It's even a lot faster with the next PCIe generations, such as PCIe 4.0, PCIe 5.0, PCIe 6.0, which have the bandwidth throughput at 64GB/s, 128GB/s, 256GB/s, respectively.

If they are in an actual race, an M.2 PCIe SSD will leave SATA SSDs in the dust. However, it's theoretical. In reality, the transfer speed of M.2 PCIe SSDs couldn't reach that ideal number. Most new M.2 slots support up to 4x lanes of PCIe 3.0, which has a maximum transfer speed of roughly 3.94 GB/s. Perhaps M.2 slots that support x8 or x16 lanes of PCIe will appear soon enough in the short future.

Need better performance? I think you should use PCIe x16 SSDs instead of the M.2 form factor.

As for the price, M.2 PCIe SSDs are relatively more expensive than M.2 SATA SSDs. However, this isn't a great barrier that could prevent users from purchasing M.2 PCIe SSDs. With a limited number of M.2 slots on the motherboard, most people would rather spend more money on an M.2 PCIe SSD than an M.2 SATA SSD at a lower price.

So what is your selection?

From my point of view, you should pick an M.2 PCIe SSD as it gives better performance, particularly when you are upgrading from a 2.5-inch SSD to the M.2 form factor. It makes no sense to select an M.2 SATA SSD to replace a SATA SSD. It's even better when choosing an NVMe PCIe SSD to boost the reading and writing speeds.

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