Samsung SM951 M.2 NVME SSD Review (256GB)


Crystal Disk Benchmark is used to measure read and write performance through sampling of random data which is, for the most part, incompressible. Performance is virtually identical, regardless of data sample so we have included only that using random data samples.

Samsung SM951 M.2 PCIe NVMe 256GB CDMIn Crystal Disk Mark we can see that while read and write maxed out at 1,687MB/s/1,255MB/s respectively, random read speeds are much higher than the AHCI variant. 512K read has improved 100MB, 4K read has increased 8MB/s, and 4K QD32 performance went up over 150MB/s. 4K write speeds are also almost 50MB/s faster! This performance is great to see!


The toughest benchmark available for solid state drives is AS SSD as it relies solely on incompressible data samples when testing performance. For the most part, AS SSD tests can be considered the ‘worst case scenario’ in obtaining data transfer speeds and many enthusiasts like AS SSD for their needs. Transfer speeds are displayed on the left with IOPS results on the right.

Samsung SM951 M.2 PCIe NVMe 256GB AS SSD Samsung SM951 M.2 PCIe NVMe 256GB AS SSD IOPS

Following the trend, the Samsung SM951 NVMe reached a higher overall score of 2623 points. Read and write max out at 1.9Gb/s and 1.2GB/s respectively. 4K read is also 52MB/s while 4K write is 168MB/s. In terms of IOPS we can see it is able to hit nearly the rated spec, coming in at 283K IOPS read and 81k IOPS write.

In the AS SSD Copy Benchmark the best speed of 1,557MB/s was achieved via the ISO test which is 50MB/s higher than that of the AHCI variant we tested previously. Program copy performance increased nearly 100MB/s as well, however, Game performance dropped down to 723MB/s, which could be due to the difference in tested capacities. Overall, great results.

Samsung SM951 M.2 PCIe NVMe 256GB AS SSD Copy


Anvil’s Storage Utilities (ASU) are the most complete test bed available for the solid state drive today. The benchmark displays test results for, not only throughput but also, IOPS and Disk Access Times. Not only does it have a preset SSD benchmark, but also, it has included such things as endurance testing and threaded I/O read, write and mixed tests, all of which are very simple to understand and use in our benchmark testing.

Samsung SM951 M.2 PCIe NVMe 256GB AnvilThe SM951 NVMe SSD achieved a Total score of 9,372 points in Anvil Storage Utilities, which is actually lower than the AHCI variant, but this could mainly be due to the lower sequential write speed. Reads max out at 1.9GB/s while writes max out at 1.15GB/s. Again we see some strong 4K read and write performance, reaching 54MB/s and 189MB/s respectively.


Iometer is an I/O subsystem measurement and characterization tool for single and clustered systems. It was originally developed by the Intel Corporation, however, they discontinued work on the program. In 2003 it was re-launched by an international group of individuals who are now continuously improving, porting and extend the product that is now widely used within the industry. This is a very powerful benchmarking tool and we are just now starting to integrate it into our consumer reviews.

Samsung SM951 NVMe 256GB Iometer 4K read_write_IOPSFirst up in Iometer we ran two workloads at a QD of 64 in order to max out performance, one was 100% random read and the other 100% random write. As you can see, thanks to NVMe, the SM951 is able to achieve nearly 300K IOPS! This is about 120K more than the AHCI variant. Write IOPs start off around 90K and drop down to an average of 10.5K, which is similar to the AHCI variant.

Now, let’s be real here, while it is great to see such high performance due to NVMe, consumers will never reach such high queue depths and utilize such high IOPS. Most of the time we will reach only a QD of 1-8. For this reason we are now going to look at the other advantage that NVMe brings to the table, lower latency. Let’s see how the AHCI and NVMe variants compare.

Samsung SM951 NVMe 256GB Iometer Average Random Latency

In order to compare we ran our standard 4KB random read-write workloads at QD32 on both SSDs. As you can see in the graph above the SM951 NVMe SSD’s read latency is 0.119ms, about 34% less than that of the AHCI variant. Again, when looking at the write latency, the NVMe SSD’s latency is 58% less than the AHCI model at 0.343ms. NVMe definitely helps to reduce latency as promised.


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    Did the SM951 NVMe throuttle down on high temperature?

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    I thought that using it with a x99 system would be the thing to strive for who buy this expensive ssd and own a z97 system i think that the people that is interested in this ssd already have a x99 or another high end system so in my view it should´t be realeased before this is solved.

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      I am a bit confused as to what your issue may be. Before what is solved?

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        that there is problem with booting with a x99 card (asrock …) yes it may be the motherboard maker that need to upgrade uefi but as i understand the article you only got it to work with z97.

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        I am not sure of which you speak but have been using ASRock boards exclusively for all of my testing of NVMe and have yet to have a problem. the only board we seem to have had difficulty with, and advised quite a few others on actually, is the ASUS boards and booting such drives as the AHcI XP941.

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        Quote”We ran into issues with it in our other test system with an ASRock X99 WS-E motherboard and UEFI version P1.4. While it would boot off the NVMe SM951, speeds maxed out at PCIe 2.0 x2 bandwidth when used in a PCIe x4 to M.2 adapter. When in the same adapter in our Z97 test bench, it performed flawlessly.” from the article above.

        If it works with my Asrock MB i will reconsider (have a asrock x99 m-atx killer) but i didn´t see anything else in the article that made me belive that it will work with my MB.

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        Tell you what… I will get that in my system for a test. Remember, that ASRock motherboard does not have a built in Ultra M.2 adapter.

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        thx you are to kind (according to asrock webpage/manual) i have a ultra M.2 onboard(36Gb)

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        Oooops apologies… The SM951 would work fine in that then as it would be a PCIe x4 slot.

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        yes it is Pcie gen3 x4 slot (M.2)

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        In another article/test you mentioned lower IOPS on Intels X99 Platform compared to Z97 motherboards. Do you have any news to this matter? Is the NVME drive showing similiar behavior? Please put it in your test system and run a quick test, I would really appreciate it.

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    Would you recommend to use Samsung SM951 or XP941 (or which one?) in older dual XEON Supermicro board (X7DWN+) using adapter card (e.g. Bplus M2P4S)? Server with this board is Hyper-V with many small VHDs and lots of backups, so why bother with SSD (requiring more space with worse performance) and not jump right to the M.2? If capacity is not an issue, price
    is worth of performance boost, isn’t it? Thanks for suggestions.

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    Erwin Thierry Klein Haneveld

    where to buy the MZVPV256HDGL-00000 ? can any one give me directions I need the MZVPV NMVE edition

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      you and me both brother, I cannot find one til this day but sure must be a question of time at this point?

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    Christopher Caruk

    Hello, I’ve just been comparing a 512GB 951 NVMe variant that I purchased yesterday with an existing 512GB 951 AHCI. Apparently it’s a sample rather than a production unit but I’m seeing fantastic read speeds but horrific write speeds. In my case I’m using with an Asus Z97i-plus with the latest BIOS. The board identifies the 951 and allows me to install windows (8.1 all latest updates)… so far so good. Unfortunately when I run speed tests against the NVMe variant I get 10 times slower write speeds compared to the AHCI variant.

    CrystalDiskMark: AHCI variant (connected to PCIe 3.0 bus)

    Seq Q32T1 – 1172MB/s read | 1043MB/s write
    4k Q32T1 – 398MB/s read | 289MB/s write
    Seq – 1052MB/read | 900MB/s write
    4k – 35MB/s write | 128MB/s write

    CrystalDiskMark: NVMe variant (connected to PCIe 3.0 bus)

    Seq Q32T1 – 2264MB/s read | 501MB/s write
    4k Q32T1 – 563 MB/s read | 21 MB/s write
    Seq – 1299 MB/read | 170 MB/s write
    4k – 54 MB/s read | 0.98 MB/s write

    Blindingly fast write but horrifically slow write speeds.

    I’ve also tested using the Z97i-plus’s M.2 slot. I see reduced read speeds due to the limited, 10Gbps, speed of the M.2 on this board but the same horrific write speeds (even my Corsair SATA SSD is faster than this).

    Is there something that I might be doing wrong? Could this be a BIOS problem? A Windows NVMe driver problem?


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      Asle Bie Andersen

      Here is the fix!
      I have Sm951 nvme 512GB on Rampage V 🙂

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      What kind of reduced speeds in the M.2 slot are you getting for both NVMe and ACHI? I have the Z97I-Plus also and am wondering what I could expect compared to the professional reviews or if the 10Gbps limit makes the differences between NVMe and ACHI irrelevent?

      Also, did you find a fix for the write speeds of the NVMe variant? Was Asle Bie Anderson’s suggestion the source of the problem?

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        Christopher Caruk

        The recommendation was good but was not the entire cause of the problem. I also found that there was something about the version of Crystal Disk Mark that was distorting the results. Once I used the same version of Crystal Disk Mark as was used in this review, the results were consistent with the results reported here.

        Re the speed… You pretty much max out the M.2 port on the Z97i plus. Regrettably the samsung will perform better than the asus so you are somewhat constrained by the asus M.2 connector. I eventually got the samsung AHCI variant for the M.2 slot and a NVME variant that I plugged into the PCIe slot. The combination is fast… Very fast. So yes, the 10 Gbps limit does make the difference somewhat irrelevant . I suspect that the lower latency of the NVME variant makes it faster but I perceivable so.

        I’m looking forward to trying the new Z170 board with my system and hope that it’s available soon.

        As an aside.. You can boot from either the PCIe or M.2 on the asus z97 using the latest BIOS.

        I have also tried the Asus H97 board but when using to dual boot there is something wrong with the latest BIOS that causes it to replicate boot devices every time you enter the BIOS. It does this until the boot device table fills up and the board will no longer boot at all. So… Avoid the H97 board if trying to do anything sophisticated.

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        Do you happen to have any numbers that you could post of each drive in the M.2 slot and each drive in the PCIe slot?

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        I’ve not done those specific comparisons but I could run a test of the 265GB AHCI in the M.2 slot and the 512GB NVMe in the PCIe slot and post tomorrow, if that would help. One of the problems with having the M.2 onto bottom of the board is that you have to disassemble the system to get at the SSD. In my case I have all of this stuffed into a HD-Plex HS.1. Wonderfully small but tricky to open and close.

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        That would probably help. I could compare that to the numbers in the article and yours above to get a close guess on whether the NVMe is worth waiting/hunting for or just go ahead with the AHCI.

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        Christopher Caruk

        Either way. you will not regret getting one of the 951s. They are by far the fastest SSDs I’ve every used (normal I buy the 850 pros). If it helps… I think that, once the new i76900 and Z170 boards are available I’ll go with a pair of the 512GB NVMe 951s… one on PCIe and the other on the M.2 slot. The new M.2 slots is supposed to be 4x so if the performance is similar I may even try RAIDing them.

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        AHCI will suffice and give you performance you seek, however, consider the makeup of the machine. As Only NVMe is the only true animal built for SSDs, using AHCI is somewhat like putting a Ford engine into a Chevrolet. It may work perfectly and without issue for the long term, however, one simply. Ant beat the native build.

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        I am planning to get the Asus Z97I-PLUS and wondering what should i buy, the Samsung SM951 256GB M.2 PCIe NVMe or the Samsung M.2 (2280) 850 EVO 500GB SATA SSD to plug it in the back of the borad m.2 slot and to install windows on this ssd.

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    Does anyone have any recommendations for a PCIe card to run one of these Samsung drives? I’d love to stick one in my Dell r610 server to run an application server… non business critical so redundancy isn’t needed…
    Bplus M2P4S ? any other recommendation?

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    I got a Gigabyte GA-Z97-UD5H-BK Just learned about this… whats your recomendation for my board… nvme or ahci .. i read somewhere that it does boot to this drive with a little work…

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    Hello everyone, I am building a new skylake pc and the motherboard I bought supports nvme (z170 deluxe). I have my eyes on this small disk but I have also seen the temperature readings during the tests.

    I am planning to buy one as soon as it is available and stick small heatsinks on the memory chips (there are a lot of options on ebay).

    Can the reviewer give some information about the dimensions of the disk and some approximation for the chips (20mm? 14mm?)

    thanks in advance!

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    I am planning to get the Asus Z97I-PLUS and wondering what should i buy, the Samsung SM951 256GB M.2 PCIe NVMe or the Samsung M.2 (2280) 850 EVO 500GB SATA SSD to plug it in the back of the borad m.2 slot and to install windows on this ssd.

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      If you buy the Z97I-PLUS don’t plan on getting the full read/write speeds the SM951 is capable of because the M.2 slot located on the bottom of the board only supports PCIe 3.0 x2. I have the board currently and have checked the specs and other forums. You will still get good speeds around 700 or so. The M.2 EVO gets around 550 so speedwise you would want the SM951 and then upgrade your board later down the road. (There aren’t many ITX boards that support the PCIe 3.0 x4). If you want more storage with decent speeds go for the EVO.

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    Does anyone know when the NVME version will be available to purchase online? thanks

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    How do I get the MZHPV to boot on a desktop with an adapter? I shows up in Disk Management as Disk 0 with an OS on it that I cloned from another drive. But it won’t boot. The BIOS doesn’t see it at all. Help.

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    Where can I buy compatible USB 3.0 case for this drive so I can use it as external drive?

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      Help! I am looking for the same… Now that my XPS has crashed dead, I am looking to read this SSD hard drive externally, but I can’t find any USB cable that’s compatible with this particular M.2 2280 form factor. Anyone knows what manufacturer has finally started selling USB adaptors or enclosures that are compatible with this set of pins?

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    When they will have the M.2 NVMe format 2260 for Laptos and some motherboard ITX?

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    What I mean is that there is no NVnvme 2260 format, which is used by some ITX motherboards and laptops. The 2260 size format does not yet exist on the market

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