Can You Insert Your M.2 Drive Into the PCIe Slot? (Does It Fit?!)

Figuring out storage solutions seems like it’s only getting harder. File sizes, including video games, are only getting bigger and this means that we need to expand our storage options more frequently. This has got a lot of people asking can you insert an M.2 drive into a PCIe slot?

You can insert an M.2 drive into a PCIe slot only if you use an adapter. M.2 drives are designed to fit into M.2 slots only. Using an adapter to connect an M.2 drive to a PCIe slot can cause performance issues with your storage and your motherboard.

Here’s why an M.2 drive can’t be installed into a PCIe slot and what your options are for working around this problem.

What Are M.2 Drives, Anyway?

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

If you’ve been around PC Building in the last few years, you’ve probably seen M.2 drives around. These are a new type of drive that has changed how we look at the storage on everything from tablets to PCS.

The M.2 is a designation that tells us the form factor of a drive. M.2 is really just a measure of sizing, and not a commentary on what the drive is actually used for. It’s just that the most common use for M.2 drives has been in creating some of the fastest solid-state storage options out there.

Those connectors on the end of your M.2 drive look a lot like a PCIe connection – especially the smaller PCIe x4 slot:

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

This has caused a lot of confusion for people who are building their own PCs. Can you connect your M.2 drive to the PCIe slot? Well, in order to answer this question we need to talk about M.2 drive keying and what PCIe slots even are.

What Is An M.2 Drive Key?

M.2 keys might sound like something you need to unlock the drive, but they actually refer to how the contacts on the drive are “keyed” like the teeth of your house or car keys. If you look at the gold contacts on your M.2 drive, you’ll notice that they are notched at either end—or both.

That’s the keying for your M.2 drive. M.2 drives can either be B, M, or B+M keyed. The B+M keyed M.2 drives can work with any M.2 drive slot, but B or M drives need to work with their corresponding slot. A B M.2 slot will not be able to detect an M keyed M.2 drive, for example.

There are actually 12 other keyings for M.2 drives, but those apply to other devices and not the storage options we’re talking about today.

What Are PCIe Slots?

Using the highlighted PCIE slot for the GPU could overheat the M.2 slot below it
The arrow here points to a PCIe x16 slot

PCIe stands for peripheral component interconnect express and it constitutes a standardized high-speed port that connects peripheral devices to your motherboard. This can be a Wi-Fi card, graphics card, storage, or a variety of other devices. PCIe slots let you get maximum performance out of devices that used to require slower connections.

Each PCIe slot has a different amount of lanes. These lanes are the physical connection that bridges the gap between the motherboard and the device plugged into the PCIe slot. These can be single-sided or double-sided.

Can You Insert M.2 Drives Into PCIe Slots?

It’s easy to get confused by which drives fit into each slot, especially because M.2 drives often advertise that they are “PCIe 4” or “Gen3” (meaning PCIe 3):

A GEN4 M.2 SSD means that it supports a PCIE 4.0 slot in the motherboard
A GEN4 M.2 SSD means that it supports a PCIE 4.0 slot in the motherboard

But you cannot insert an M.2 drive into a PCIe slot without an adapter. M.2 drives require their own slots that fit their unique form factor. M.2 drives are simply the wrong size to fit into a PCIe slot that isn’t designed to accommodate an M.2 drive.

Despite using PCIe technology, the PCIe slots on your motherboard can’t hold an M.2 drive. This is because they are designed for physically larger cards like Wi-Fi or graphics cards.

There are adapters that let you connect an M.2 SSD to your PCIe slot, but those might cut into the performance of your M.2 drive or raise other compatibility issues with how your motherboard assigns roles to each PCIe and M.2 slot.

Let’s take a closer look at connecting an M.2 drive to a PCIe slot.

How You Can Insert An M.2 Drive Into A PCIe Slot

First things first, you probably shouldn’t try to connect your new M.2 SSD to a PCIe slot with an adapter. This is because your new M.2 drive is locked into the performance of the slot that it is connected to. The best M.2 drive in the world won’t get good performance outside of its designated M.2 slot.

If you’re still determined to make it work, then we’ve got some options for you.

M.2 To PCIe Adapters

These are adapters specifically designed to connect M.2 to PCIe slots. These adapters are typically fairly large and have a simple way of functioning.

All these adapters are doing is routing an M.2 slot through your PCIe slot. The adapter is essentially just a PCIe card with an M.2 slot attached to it:

This can be a good work around if you’re determined to get your M.2 drive working through a PCIe slot, but you could suffer speed and performance issues by choosing this option.

Another thing to consider is that there are adapters that can accept multiple M.2 slots. This means that you can connect multiple storage options to a single PCIe slot. This might cause performance issues because most motherboards aren’t designed to handle this kind of storage configuration, but this could give you an option to add more storage if your storage needs are particularly high and other options aren’t available.

M.2 To SATA Adapters

There’s another option to consider, but it’s going to come with a pretty noticeable performance decrease.

Your old SATA SSD is pretty much just an M.2 storage drive with a slower physical connection. If you happen to have extra M.2 PCIe SSDs lying around, you could connect them through your SATA ports.

This would require you to get an adapter that allows you to connect your M.2 SSD through SATA port. There’s something a little bit ironic about these adapters. All they really are is the housing for an old SATA SSD that has an M.2 slot where the old storage chips would be:

Using an M.2 to SATA adapter is essentially just recreating an old SATA SSD, but with more set up steps and more money. This definitely isn’t the best use of your M.2 drive unless you happen to have extras and you have no alternatives.

If you’re considering expanding your storage and getting an M.2 to SATA adapter, you should probably consider an alternative. These adapters are going to lock your M.2 SSD speeds into the speeds that a SATA connection offers. You’d be better served just buying a SATA SSD which could give you a much higher storage capacity anyway.

An older SATA6 SSD with SATA cable attached
An older SATA6 SSD with SATA cable attached

This brings us on to some alternative options to consider.

Alternative Options To Consider

If you’re thinking about plugging your M.2 SSDs into your PCIe or SATA ports, you’re probably looking for ways to expand the memory and storage capacity in your computer.

These workarounds come with plenty of problems. Your motherboard simply isn’t configured to accept M.2 storage through your PCIe slots— even though it can work. Connecting M.2 storage drives through your SATA port also creates some problems though these are mostly related to slower speed and lower performance numbers.

An alternative option to consider is to Simply add SATA SSDs to your computer. This will give you more storage opportunities that still have a good speed. A few SATA SSDs are a great choice for housing files and programs that you don’t use regularly, but you’d still like to store on your computer.

You can also try external storage options. These are getting increasingly fast and make an excellent way to store large files that don’t have to bog down your PC.

cropped A picture of me Tristan
About Tristan Perry

Tristan has been interested in computer hardware and software since he was 10 years old. He has built loads of computers over the years, along with installing, modifying and writing software (he's a backend software developer 'by trade').

Tristan also has an academic background in technology (in Math and Computer Science), so he enjoys drilling into the deeper aspects of technology.

Tristan is also an avid PC gamer, with FFX and Rocket League being his favorite games.

If you have any questions, feedback or suggestions about this article, please leave a comment below. Please note that all comments go into a moderation queue (to prevent blog spam). Your comment will be manually reviewed and approved by Tristan in less than a week. Thanks!

8 thoughts on “Can You Insert Your M.2 Drive Into the PCIe Slot? (Does It Fit?!)”

  1. Hello Tristan, noob question here. Given that the nvme m.2 PCI express SSD leverages the PCI express technology, what is the reason why the PCI express slot on the motherboard does provide a slower performance than the m.2 slot? Or is it the adapter m.2 to PCI express that slows down things? Thank you very much for answering. Francesco

    Reply
    • Hello Francesco, great question. In theory PCIe and M.2 will perform the same for the reasons you outline (i.e. it’s the same underlying lanes) but sometimes motherboards might prioritize the M.2 lanes – and other times, an adapter might slow things down slightly. However this all varies depending on the exact hardware, hence why I kept this area vague and just said “could” 🙂 You’re right though that in theory there should be no real difference.

      Reply
  2. Just wanted to say that this was a very well produced article. You answered not only the question I had, but even went as far as trying to understand WHY someone would do this and suggested alternatives. Good job man, and thank you!

    Reply
  3. I’m curious, does a motherboard need to have M.2 slots in order to have the option of using a PCIe adapter? Or could a person with an older motherboard without them use an adapter to use these newer M.2 SSDs?

    Reply
    • Hey Noah, using an M.2 expansion card (i.e. that plugs into the PCIe slot) will work fine. It will give you M.2 support via the PCIe card/slot, without needing to have a native M.2 slot in your motherboard. You’re right to wonder this – it can be a good option for quickly gaining M.2 support without upgrading your whole motherboard.

      Reply
  4. Hi Tristan

    I would like to improve my laptop speeds by adding a M2 drive- however I have looked on YouTube and internet for a guide and cannot seem to find one, for my laptop model – plenty for other laptops of HP’s but not my one
    I have a HP Notebook
    I have disassembled it and checked under the HD, and other parts of the motherboard but there doesn’t seem to be one
    I am beginning to think I cant as there are no slots for M2
    Kr
    TeeceOr

    Reply
    • Hi TeeceOr,

      Could you please give me the exact model number for your HP notebook? Some models will support M.2 NVMe drives but others won’t. Worse case, though, upgrading from a mechanical hard drive to a SATA SSD should help massively too – and it’s quite likely that this upgrade will be compatible with your HP device (at least).

      Thanks,
      Tristan

      Reply

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