M.2 storage drives offer the best performance out of any of today’s PC storage options. However, there’s been a lot of confusion about what type of M.2 drives you can use with your NVMe and SATA slots.

Your M.2 NVMe storage drive can only fit into an NVMe M.2 slot. Your M.2 SATA SSD can fit into a SATA M.2 port, or an NVMe port if you have a SATA M.2 SSD with a B+M key. These drives don’t easily swap despite having the same form factor due to different physical and software technology used to make these connections.

Half the fun of building your own PC is getting to assemble the physical parts. Let’s check out why certain M.2 drives can’t work with every type of M.2 slot.

A Quick Primer On PC Tech Terms

The various types of PCIe and M.2 slots on a modern Asus motherboard

Reading through tech articles can be challenging if you’re not up-to-date on your tech terms. Here’s a quick rundown of today’s topics. You might be surprised by the specifics and facts behind a few of these common PC terms.

Consider this a firmware update for your techie vocabulary.

SATA

SATA, or Serial AT Attachment is a slightly out-dated physical connection between storage drives and your motherboard. SATA is a computer bus interface that was created in 2000 by the Serial ATA Working Group to replace the previous PATA standard.

SATA is capable of impressive speeds even now. SATA connections with an SSD are more than capable for tackling some of the most demanding tasks, but they have recently been outclassed by a much faster connection protocol.

NVMe

NVMe is short for Non-Volatile Memory Express and is also a type of bus connection. These drives usually attach via the PCIe bus, but that bus also accepts the newest type of SATA drives. NVMe is the successor to SATA due to being capable of much faster speeds.

PCIe

PCIe means “peripheral component interconnect express”, and it’s an adaptable connector which allows you to add devices to your motherboard. This includes WiFi cards, graphics cards, storage and more.

M.2 Storage Drives

Two M.2 NVMe drives installed in an Asus B550 Plus motherboard

M.2 is most commonly thought of as a type of hard drive, but this isn’t technically correct.

M.2 is actually just a form factor. It’s a specific range of sizes and shapes for drives. M.2 is standardized to allow computer designers to create uniform tech. M.2 adapters are standardized for the same reason that electrical outlets are—it would be chaos if each outlet in your home had a different plug requirement.

M.2 has a smaller form factor than most previous computer storage. This creates a major advantage for PC builders who are looking to create a machine that’s got a modest footprint but serious power. M.2 drives do have a reputation for getting much hotter than SSDs.

Does The M.2 Format Support Both SATA and NVMe?

Now we can get into the heart of the issue. There’s a lot of questions around whether or not the M.2 format supports both SATA and NVMe. We’re going to dispel the myths and look at the physical science behind the M.2 format as well as SATA and NVMe connections.

Yes—But Not In The Way You Might Be Thinking

An older SATA6 SSD with SATA cable attached

The M.2 format supports both SATA and NVMe data transfer protocols. M.2 is simply just a form factor that defines a physical size and physical connection type. This means that it can use a variety of different data transfer protocols.

M.2 might support both, but that doesn’t mean that M.2 drives can work with both technologies. The specifics of your M.2 drive might make it unable to work with one or the other. There are some M.2 drives that can even work with both.

Let’s find out why M.2 drives have been causing so much trouble for people building their own PCs or updating their laptops.

Will NVMe M.2 SSDs Fit SATA M.2 Slots on the Motherboard?

There is no way to connect an NVMe M.2 SSD into a SATA M.2 slot. This is both physically impossible, as well as logically impossible. NVMe M.2 SSDs can only ever work with PCIe slots that are designed to accept the NVMe protocol.

Here are the specifics as to why these connections aren’t just universal.

Physical Connections

An M.2 PCIE4 SSD with a third party heatsink attached to it

Despite the M.2 form factor being very consistent, there are actually different types of physical connections on the end of your M.2 drive.

There are currently 12 different connections, or M.2 Keys, for M.2 drives. PC builders are typically only ever going to encounter three of these. B, M, and B+M connections are all reserved for SSDs.

What about the other 12? You probably won’t see these while building your PC. About one third of them are reserved for future use and the rest are devices that aren’t used for storage.

You just can’t physically connect B and M M.2 keys. They are incompatible and will not work properly with your motherboard. A B+M key works with both B and M ports.

You can never flip an M.2 drive to make the key fit. While this might make it physically plug in, it will no longer work and you could break your brand new tech.

Related Reading: Should I Use The M.2 Heatsink With My Mobo (Or A Separate One?)

Data Transfer Protocols

A PCIE M.2 drive running at a good temperature below 50 degrees celcius

There are also software reasons why NVMe drives can’t be plugged into SATA slots.

These are just two, different and competing protocols. They have different physical, technological requirements when they connect.

This means that even if you could successfully fit an M.2 NVMe SSD into an M.2 SATA slot, you won’t be able to use it. The technology that controls SATA is just not capable of utilizing the NVMe technology.

Here’s another way to think about this. A CD and a vinyl record are both ways of storing audio information, but you couldn’t get a CD player to play a record. It wouldn’t physically fit and the CD player just doesn’t have the technology to get the audio information off of the record.

Things get really interesting when we look at this problem from the other side.

What About Fitting SATA M.2 Drives In NVMe M.2 Slots?

Installing an M.2 NVMe SSD in my Asus motherboard

Here’s where the analogy that we just came up with stops working. In this case, it turns out that you can plug a SATA M.2 drive into an NVMe M.2 slot. There are a few things that we need to get right before we can try to make this work:

  • The first is that it has to be an M.2 SATA SSD with a B+M key. This is the only way we can make the physical connection work. B+M keys fit both B and M slots and we need that versatility to make the connection.
  • Next, your motherboard has to be able to accept SATA and NVMe in that slot. This is specific to the make and model of your MB, so check your motherboard’s owner’s manual for the specifics of what works in your drives.
  • Now we’re plugged in and working, but what’s going to happen with our SSD drive? Well, it’s going to get maximum speed. That versatile NVMe slot is like a super-charged SATA slot. It’s going to let you make the most out of your SATA drive.

This is one reason why it could be beneficial to connect an M.2 SATA drive this way. This lets you get great performance, but still save by buying an “older” style of drive.

Can An M.2 SSD Fit Into A PCIe Slot?

While we’re here, we should talk about trying to fit an M.2 SSD into a PCIe slot. After all, those M.2 Keys we talked about earlier are pretty visually similar to your PCIe slot which makes plenty of people think that you can just plug them right in.

However, and you might be able to guess this one, your PCIe slot uses different physical and logical technologies to make the connection work. This means that it just won’t be able to work with an M.2 drive. The connection will be too physically weak and there’s just not a system in place to read the data on your drive.

You can purchase converters that allow you to make these connections. You’ll likely wind up sacrificing on speed and performance using these slot converters, but they will let you work around having limited space on your motherboard when you’re in a pinch.