Samsung SM951 NVMe M.2 PCIe SSD Review

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Samsung SM951 NVMe 256GB  M.2 PCIe SSD Testing

The Samsung SM951 AHCI M.2 PCIe SSDs might be the most talked about enthusiast SSD at this moment, but what about the Samsung SM951 NVMe drives? If you thought the OEM-only Samsung SM951 AHCI drives was tough to purchase you will likely lose some hair trying to find someone that has the Samsung SM951 NVMe drives available to purchase today. Though the SM951 NVMe drive is not available through retail channel just yet, we managed to get our hands on one and have been using it on a number of systems over the past few weeks.

Samsung SM951 NVMe SSD

The drive we received is the Samsung SM951 NVMe 256GB M.2 PCIe SSD that is listed as model MZ-VPV256 with the full part number of MZVPV256HDGL-00000. This is one of the new SM951 NVMe-capable devices. The Samsung SM951 series use the PCI Express 3.0 x 4 interface and feature Samsung UBX 3-core controllers that are paried with 16nm MLC NAND Flash memory. This combination on the new NVMe-based SM951 SSD achieves sequential data read and write performance up to 2,260 MB/s and 1,600 MB/s! The peak random 4K Read performance is said to be up to 300,000 IOPS, but for some reason the write IOPS are not given.

Samsung SM951 NVMe M.2 PCIe SSD Drives
Part Number Capacity and Features Sequential (R/W) Max 4K IOPS (R/W) Price
MZ-VPV128 M.2 Form Factor 128GB 2060/650 MB/s Up to 300k IOPS unknown
MZ-VPV256 M.2 Form Factor 256GB 2260/1260 MB/s Up to 300k IOPS unknown
MZ-VPV512 M.2 Form Factor 512GB 2260/1550 MB/s Up to 300k IOPS unknown

Samsung SM951 NVMe M.2 Features: 

  • PCIe Gen4 8Gb/s Interface, up to 4 Lanes
  • Compliant with PCI Express Base Specification Rev 3.0
  • Compliant with NVMe Express Specification Rev 1.1a
  • Power Saving Modes: APST & L1.2 Mode
  • Support Admin & NVM Command Set
  • End-to-End Data Protection
  • RoHS Complaint
  • Support up to 1 Namespaces
  • Support up to 8 I/O Queues
  • Support up to 15K Queue entries for each I/O Queue

Samsung SM951 NVMe SSD PCB

The back of the SM951 NVMe 256GB M.2 drive has no NAND Flash packages or components on the back. The Samsung SM951 NVMe has a MTBF rating of 1.5 million hours.

samsung-sm951-nvme-controller

Here is what the front of the Samsung SM951 NVMe 256GB M.2 SSD looks like with the label removed. You can see two 128GB NAND packages that make up the drives 256GB of storage space. You can also see the Samsung UBX controller and 512MB DRAM cache chip that were hidden before we removed the label.

 

k9ukgy8scd

The two 16nm NAND chips on our Samsung SM951 NVMe 256GB drive are labled K9UKGY8SCD-DCKO. These are the same exact NAND Flash memory that is used on the AHCI drives, so the NVMe and AHCI drives use the same Flash. Samsung has plans to incorporate its next-generation 3D V-NAND technology into its NVMe SSDs, but they have not said a firm date as to when that change will be happening.

Samsung UBX Controller

The Samsung UBX controller is ARM-based 3-core SoC that was labeled S4LN058A01-8030 on our test sample. The Samsung SM951-NVMe has adopted the L1.2 low-power standby mode (which allows all high-speed circuits to be turned off when a PC is on sleeping mode or in hibernation), as defined by PCI-SIG, the PCIe standards body. By embracing the L1.2 level of standby operation, the SM951’s power consumption is drastically reduced – to under 2mW, representing about a 97 percent decrease from the 50mW consumed using an L1 state, which is the most widely used low-power mode today. This is a big deal in mobile devices like ultra-slim notebook PCs where battery life is of utmost performance. Typical active power usage is 6.5 Watts and typical average idle is 50mW.

Now that we know the basics of the Samsung SM951 NVMe we can take a look at performance!

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  • NexxtBs

    @MikeO55:disqus Thank you so much, my writing speed with my PM951-Drive in my XPS 15 9550 was really terrible, and thanks to you I tried downloading the NVMe 950 Driver and now the computer flies, I really mean it, is so much faster. Everyone else try it with the NVMe Driver here: http://www.samsung.com/global/business/semiconductor/minisite/SSD/global/html/support/downloads.html

  • Michael Owen

    Noticed that PCMark 8 was on special offer on STEAM (80% off) so purchased it and then ran it against the SM951. Was initially a bit disappointed to see that the results were very similar to those initially.
    IE. Storage Score: 4437 & Bandwidth 102.97 MB/s

    So out of interest I re-installed the NVMe driver for the Samsung 950 pro and got:

    [URL=http://s198.photobucket.com/user/mikedowen/media/PCMark%208%20Samsung%20NVMe%20driver_zpsp4wqahq9.jpg.html][IMG]http://i198.photobucket.com/albums/aa200/mikedowen/PCMark%208%20Samsung%20NVMe%20driver_zpsp4wqahq9.jpg[/IMG][/URL]

    So looks like running with the Samsung driver is the way to go.

  • Michael Owen

    Here is a run of AS SSD. Looks just fine to me.

  • Michael Owen

    Since the firmware update in July, the FUA “issue” is now a non issue.
    The problem that legit experienced while running AS SSD is because they must have installed it somewhere other than on the C: drive. If you do this then while the read side of the app will work, the write side wont (it just hangs). Somewhat stunned that they did not realize this! I fell for this one myself once, as my download folder is on another internal drive, so without thinking… I unpacked the cab and installed it here. Low and behold, I had the same problem as Legit. Install it on the C: drive and it ran just fine. All metrics as expected. If you don’t believe me, try it.

    I have been running one of these drives now on a Skylake platform as a boot drive for some 4 months now and it absolutely flies. Boots to a usable desktop in 13 seconds flat! Though I suspect Windows hybrid shutdown and MSI fast boot help a bit as well. No problems at all and all test show it fairly races along.

    Just downloading the latest version of PCMark and I’ll post the results up when ready.

    Only real downside to this drive, is that it is truly an OEM system product (not really meant to be sold to the general public) so little (read none here) support from Samsung. As such, most home PC enthusiasts are probably better off getting the Samsung 950 pro, as this is a retail product.

    • James Lloyd

      Dear Michael, could you please let me know where/how you downloaded and installed this firmware update. I can’t find any resources on the SM951 NVME other than some guides on physical installation.

      • Michael Owen

        Hi.. you can’t update the firmware on these drives unluckily. It’s just that mine is one of the later drives and came with the latest firmware mentioned in the Legit review.

        Again unluckily, you wont find much (read pretty much “any” ) support for these drives. As they are OEM system builder parts and not really intended to be sold directly to retail customers. No way to read the SMART data, no way to update the firmware, warranty resides with the re-seller (IE. not Samsung), no retail packaging etc. etc.
        O/L shops really should be aware of this and highlight the fact in their advertising etc.

        The consumer version of this (IE. retail version), is the Samsung 950 pro. Which is fully supported by Samsung.

        Not much help to you I know. But people need to be aware when buying true “bare bone” parts like this, what is really involved.

        PS. Not run PCMark, as I would need to purchase the full version to get the storage test and it’s not worth it. But Legit has now updated their review, showing that the FUA issue has been resolved by a later firmware update.

        • Michael Owen

          Maybe worth mentioning that the NVMe driver fo the Samsung 950 pro will also install and work for the SM951. So if anyone is still having problems, then this might be worth a shot. I tried it… but it did not seem to make any difference in the performance. So I reverted back to the native Windows 10 NVMe driver. Which in my case at least, appears to work just fine.

  • darren evans

    so that’s it?? People like me with this crap have to just deal with it? It performs terribly. Boot times are horrendous. Far slower than my previous 850 pro

  • Minkyu Kim

    If you finding a tool to get SMART with Samsung NVMe devices, Naraeon NVMe Tools can be reasonable option.
    http://naraeon.net/en/latest-nvme-tools

  • Acer_Predator

    Guys I have purchased this crap ssd and speeds are even worse than AHCI !

  • SizLion

    Anyway you can share what the original and new firmware revisions were?

    • Carenotbutpleasefeelfreetotrol

      Sorry I could not say, but I can say that mine have got BXW7 and drive have got the date July 7 – 2015 on it so not very old.

      • Lukadlo

        Just bought this SSD (SN starts the same BXW7300Q 2015.09) and I must say, that I face the same issue. The PCmark8 and AS SSD show terrible write speeds. Other benchmarks like ATTO show correct speeds..

  • 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 951.

    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/s 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/s read | 170 MB/s write
    4k – 54 MB/s read | 0.98 MB/s write

    Blindingly fast read 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.

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

    Also… I’ve never been able to match the the read speeds that you posted but I’m seeing a maximum of around 1100MB/s read speed on the AHCI variant.

    Could this be a limitation of the board or a misconfiguration of the PCI bus?

  • theUnhandledException

    Ouch. I had been holding off on SM951 AHCI to see what the NVMe version could do. The “FUA/driver/write performance” debacles is disappointing but to be expected given how new it is. NVMe is obviously the way forward but in the interim I may grab a 256GB AHCI version and wait to see how the M.2 NVMe space develops. Thank for this review. I would have been annoyed to discover this issue after the fact. I also think it was shady for Samsung to only report the 4K read numbers (because they KNEW the write number were horrible).

  • Erwin Thierry Klein Haneveld

    its because the NVME by samsung is an oem device so its upto the oem retailer to make the driver for it!

    • Nathan Kirsch

      That is correct when it comes to utilities that run say the TRIM command, but for an actual Windows NVMe driver that would fall on Samsung!

  • JayFiveAlive

    At least the Intel 750 NVMe SSD has drivers… Samsung will never have drivers? From the way people were talking the 951 NVMe was supposed to be a fair bit better than the 750.

    • Nathan Kirsch

      Samsung obviously doesn’t have a drive for the SM951 NVMe, but they are looking into it. I wouldn’t be surprised that the next NVMe drive by Samsung has a driver set.

  • TAS

    How were you able to verify that the commands issued by the OS resulted in CMD1.CDW12.FUA being set to 1? (per the NVM Express specification)
    Or is that a hypothesis that the Microsoft NVMe driver sets the FUA bit on all writes?
    Disabling write caching implicitly through FUA would be quite disastrous to the performance of so many NVMe devices that it’s hard to imagine Microsoft would make such a change.

    • Nathan Kirsch

      Samsung themselves gave me the data with FUA enabled and disabled, so I am fairly confident that they know what they are doing!

  • TAS

    AS SSD uses FILE_FLAG_NO_BUFFERING. That’s why the writes are so low. Caching is disabled by the benchmark, by design. The website for AS SSD states this.

  • FXi2

    Too many risks and lack of support for the gains.