Is an M.2 drive faster than an SSD?

DoctorK12008 used Ask the Experts™
I have a Dell Precision Tower 5810 with 16G memory and a Samsung SSD 850 hard drive.   I plan to upgrade Windows 7 Pro to Windows 10 pro.   My MB does not have an NVMe slot, so I would need an adapter for an M.2 drive.   Is there a significant speed advantage to using an M.2 in place of the existing SSD, given that I do not have an NVMe slot?
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Distinguished Expert 2018

Apples and oranges.

M.2 is a set of physical specs and can interface tieh PCI Express, Sata, or USB.

NVMe is a logical device interface specification.

You can buy m.2 drives that use NVMe over PCI Express.  Or you could buy m.2 drives that use AHCI over Sata.

Similarly, you can buy non m.2 drives that also sue AHCI or NVMe.  So it's a false equivalency.

SSDs come in manybfoem factors and m.2 drives are a subset of that.  They aren't *nit* SSD drives.

Whether you'd get a performance boost depends on the existing drive it is replacing (not just model, but specific specifications) and what adapter you use to install the m.2.

If you are going from an SSD using AHCI over an internal Sata port to an NVMe M.2 drive that is attached to a PCI-Express adapter that gives for lanes to the drive and the OS supports it (and the computer boot firmware  firmware if you plan in booting from it) then yesz you'd get a performance boost.  But that's a lot of ifs.
Distinguished Expert 2017

You would be using a SATA cable with an Adapter through which you will be connecting an M.2 Device to your system.
Or are you talking about a PCI-X card with NVMe port?
The different between an SSD and the M.2 device is the throughput each has through the connection it has to your system.

Access within the ssd and the M.2 based solid state storage is at memory speed
The spec on the M2. is much better than the SSD SATA cousin.

You are considering the following, get a fast storage, an M2, connect it through an ADapter (which by its nature will add overhead translating SATA requests into a data stream send over to the M2

In trying to provide supporting reference, you have to make sure that the purpose for which you are buying the adapter that it is supported,
Was searching for a SPec on an adapter to determine what its impact be on the throughput of the sata I/II/III 1.5/3/6GB/s rate and the performance of the SSDs which are commonly in the 500-600MB/s read/write performance while an M.2. read/wrinte performance is in the 2000-3000MB/s

The interface/speed/bandwidth that is available to a resource is what dictates whether it is faster or not.

IMHO, if you do not have an M.2/NVMe slot on your system, buy an SSd and save a few bucks, instead of getting an M.2 at a slighly higher cost, whose sepc reflect a much higher performance ability and an M.2 to SATA adapter whose performance will be likely less than the SSD.

To complicated things further from stated above, besides the connectors and standards, the piece of hardware itself, can have speed differences. Meaning a much slower SATA model, backed with GOOD electronics, can beat a supposedly faster NVMe version with BAD electronics. Usually the price is an indicator though. You'll have to read reviews and check user benchmarks to be sure.
Also check what performance bottlenecks exist in your current setup. Sometimes it's not worth going for the highest specs if bottlenecks prevent it from being used optimally in your setup anyway.
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Distinguished Expert 2018


There are PCI-Express adapters that offer m.2 connections and the full benefit of NVMe. I definitely would not assume an adapter is SATA.  That's why it is one of those "ifs" I mentioned.  Even a very old Bios system would get full data NVMe performance as long as the OS has drivers for the adapter.

If the computer is newer and uses UEFI, they'll *usually* support PCI-Express slot adapters natively (one if the benefits of UEFI (and offload the details of the interface to the adapter itself.  Meaning you can even get OS and boot performance increases with a PCI NVMe adapter. The motherboard does not need an m.2 slot with NVMe support to get those benefits.

As to the overhead of an adapter, it'd be the same as the overhead on a MB slot itself.  As I said above, NVMe is a logical spec, not a physical spec.  When an m.2 slot that supports NVMe is embedded on the motherboard, it is using four PCI Express lanes and the PCI Express chipset of the motherboard.

An adapter in a PCI Express slot is using the exact same components as far as the MB is concerned.  In both cases there are small ASICS handling the handoff between m.2 and PCI-Express meaning that overhead is the same whether on an adapter or on the motherboard.

So it really depends on other factors which we simply cannot predict or know from the OPs post.
Distinguished Expert 2017

Hi Cliff,

I was typing my response while you posted yours.

That was covered in my post question.
one does not commonly reference a PCI-X card with NVMe support as an adapter. or at least it is not my understanding.
My understanding of M.2 adapter would be to use the SATA connection.
if the SATA port on the MB is a 12GB port while the ssd is a 6GB , so long as the "adapter" performance is comperable to the new SATA speed, the M.2. might improve.
BUt the question I would pose is whether the additional expense of additional pieces is justified on a workstation whose use is unclear.
Distinguished Expert 2017
To make things clearer, base on technical terms an M.2's performance is much better than a SATA connected SSD.


Thank you, finally a simple answer!
Distinguished Expert 2018

That's not true though. There are absolutely m. 2 drives and and m.2 motherboard that USE Sata instead of NVMe.  You ant use those terms interchangeably at all..

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