NVMe -v- SSD From Factor (2025 Update)

That only supports M2 SSD devices. An M2 SSD is the same as a "vanilla" SSD but in a different physical form. They run at 6Gbps maximum.

You need an NVMe device to run faster. That needs an NVMe compatible caddy. You can buy dual protocol caddies that support NVMe or SSD to USB.

It's best to consider M2 SSD as deprecated, you can still buy them new but they are probably old stock and the big names will now only be making NVMe devices.

NVMe *is* SSD, in the M.2 form factor. I think by SSD you mean '2.5" SATA SSD'.

It doesn't, it's an adapter for an M.2 SATA SSD to the 2.5" form factor. It's just a form factor adapter, it doesn't convert NVMe to the SATA protocol.

No, it supports M.2 SATA SSDs, which speak the SATA protocol at 6Gbps. It doesn't support M.2 NVMe SSDs.

I think you mean M.2 SATA SSD there. I'd expect that M.2 NVMe nowadays is going to be cheaper than an M.2 SATA, which is increasingly niche.

Theo

I was very surprised to find my used HP laptop came with an NVme

Couldn't tell the difference to SSD in normal use.

Thanks for all the input :-)

At the moment this is a bit of a mystery as when I looked a day or so ago the device was over £40 and I'm pretty sure it referred to NVMe, it doesn't now though.

I find the naming very confusing, to me SSD is in the format of the old spinning laptop drives and NVMe the long strip storage device, if there's a better way please let me know!

No, you're confused (aren't we all?).

SSD is the new solid state storage technology that is used instead of a spinning magnetic disc. SATA and NVMe are the two (current) ways of interfacing that storage to your computer's processor.

So you can have:-

SSD SATA - Maximum speed (currently) 6GB/s (I think) Hard Magnetic Spinning Disk SATA - Same maximum speed in theory, in practice less. SSD NVMe - Maximum speed limited by how many PCIe channels it can use, fastest

The M2 (or not) bit is to do with the low-level physical (i.e. bits of wire and/or printed circuit) between the storage and the SATA or NVMe interface.

The M2 interface bit also specifies the physical dimensions of the little PCB that the SSD hardware comes on. They come in sizes like

It's a huge can of worms!!!

So most SSDs now are M2 SSDs, and most of those are NVMe ones but it's not the only possiblity.

Now wait to find out all the things I have got wrong! :-) (I am a few glasses of wine down this evening)

That's spot on. NVMe is a way to talk to storage over PCIe, so the drives speak NVMe via M.2 slots carrying PCIe. The mobo slots often support both SATA and PCIe so you can plug in both types, but often addon cards or adapters only support one or the other. I've not seen M.2 drives that support both but there's no reason why somebody couldn't make a controller chip to do it if they wanted.

Theo

Many thanks both.

The format of a SSD drive is the same as the (old) laptop spinning drives, whereas the format of an NVMe is the long strip circuit board. The old M2 format died very quickly, I have never used one.

SSD runs at SSD speeds, about 500 MB/s and NVMe 6-n times as fast.

Problem for me is a search on Amazon returns both SSD and NVMe and they clearly don't fit into each other's slots!

Sounds like that by "format", you mean how it is presented physically - the external interface and packaging. It's in the "format" of an old laptop drive, because that way it's plug compatible with an old laptop hard drive, so you whip one out and put an SSD in. Which is what I had done to my 2014 Mac Mini. Old 500GB hard drive removed, 1TB SSD goes in. Simples.

However, newer machines will be built not needing that compatibility, so they just use the long strip "format" directly and it's faster. The thing is though, these are both SSDs - Solid State Devices.

Solid state DRIVES.

NVMe is simply another hardware/software transfer protocol, like SCSI or SATA.

It being the case that modern SSDS can fully saturate a SATA interface, something smarter was needed.

Yes, indeed, sorry if I wasn't clear.

Yes, my latest desktop has sockets for 3 x NVMe slots on the motherboard along with PCIe slots so I can add cards to take more. I think at the moment the SSD format is more flexible as it will fit any PC, my NASs and my DAS and external drive cases which is why I thought the Icy Box converter might be interesting.

There are other SSD form factors that you won't see outside of a datacentre, U.2, E.1 and E.3 (yet?)

The long strip format *are* M.2 drives (they also come in shorter versions, the numbers such as 2280 indicate the width and length).

You're probably thinking of mSATA or mPCIe?

The writing is on the wall, NVMe drives are taking over. Small ARM SoC PCs typically only take NVMe, but small SSDs are so cheap there is no reason to care, just buy what you need, when you need it.

I bought a spare 256GB SSD boot drive for £16 a couple of weeks ago.

FWIW, I did make a mistake recently. I use SATA/USB convertors and the performance is more than enough for a network disk constrained by a 1 Gigabit LAN. I assumed I could use a similar NVMe/USB convertor, but the one I bought is terrible 33MB/s transfer rate.

I also use a USB dual SATA caddy for temporarily loading random drives that I have lying about.

My current main unsolved NAS issue is stopping HDDs from spinning up when they aren't being used.

After my OP somebody replied saying "That only supports M2 SSD devices." Presumably an NVMe is not an M2 SSd device then? I've only seen markings like 2280 on an NVMe device.

You're confusing the memory type with the physical form factor.

M.2 supports SATA SSDs or NVMe SSDs by different "key slots" on the card/socket.

Well, you've only seen them on an M.2 devices, there are also NVMe devices that fit into motherboard PCIe slots, and not everything that fits an M.2 slot is an SSD, they can take USB devices like 4G or PCI devices like WiFi

AIUI M.2 supports NVMe but does not mandate it.

M.2 is a *socket*. The socket carries PCIe, SATA and USB. You can plug in things which use one of those interfaces. There are keys on the socket because some sockets are missing some of the interfaces so only certain devices will work there.

SATA is an *interface*. You can find it in an M.2 socket, an mSATA socket or via a motherboard SATA or eSATA socket.

NVMe is a *protocol*. It runs over the PCIe *interface*. You can find PCIe in an M.2 socket, in a PCIe slot on the motherboard, or via a cable.

SSD is a *type of storage*. You can find it in M.2, 2.5", mSATA form factors. Interfaces used are PCIe, SATA or USB.

HDD is another *type of storage*, commonly using SATA, SAS or USB interfaces.

So an 'NVMe' is more fully described as an SSD storage device that uses the M.2 form factor and connects to the PCIe interface, speaking the NVMe protocol.

Due to the absence of counterexamples, NVMes are SSDs, but not all SSDs use NVMe.

Theo

Nice to get full chapter and verse. So often protocols are restricted to one interface and one socket that we forget...the distinction

A fun one is an AHCI SSD. It has the 2280 form factor, it fits in an M.2 slot, it talks to the PCIe interface, but it presents to the OS as if it's a PCIe SATA controller with an attached drive - even though there's just flash chips on the board, no SATA socket.

That made it easier to work with older OSes like XP which didn't know about NVMe, and older BIOSes that would only boot from SATA drives. They had a brief flowering around 2014 but are now almost entirely extinct, as NVMe is superior in every way.

Theo