Samsung SM951 512GB M.2 PCIe SSD Review (Page 1)

Samsung SM951 512GB M.2 PCIe SSD Review

Samsung's SM951 dominates every consumer SSD on the market and in every category imaginable. This takes an early look at the future of storage.

| Jan 30, 2015 at 8:42 am CST
Rating: 98%Manufacturer: RamCity



Samsung 2014 SSD Global Summit event brought further insight into the inner workings of Samsung's 850 Pro products. At the time, Samsung teased us about 3bit per cell 3D V-NAND, this would eventually appear in the 850 EVO products that were later released. We also caught a glimpse into the future of Samsung's NVMe products. Sitting quietly in the shadows was a product called SM951, not particularly a catchy name, but one that has captivated SSD enthusiasts since we first published the image above.

In July, Samsung spoke of the SM951 as the first NVMe consumer SSD with sequential read performance of 1600 MB/s and sequential write performance of 1000 MB/s. The specifications have changed slightly from July till today. The SM951 we have in our hands and that Samsung announced availability for at CES in January is no longer NVMe, but Samsung's performance ratings increased despite rolling back to the AHCI command set.

Samsung SM951 512GB M.2 PCIe SSD Review 02 |

Availability is also tricky, at least today. At the time of writing, the only known way to purchase a Samsung SM951 is through Lenovo. Lenovo doesn't advertise the SM951 other than to show a mysterious '512 GB Solid State Drive PCIe' as an option for the new X1 Carbon Gen 3 Ultrabook. The SM951 really does put the ultra in Ultrabook though, but the $700 increase to the base $1199.00 X1 Carbon price might be a little too ultra for some.

There are some limitation to buying an X1 Carbon just to get a Samsung SM951 that go beyond cost. Lenovo's standard warranty is only for one year and I doubt Lenovo will warranty the drive after you took it out of the X1 Carbon. While the X1 Carbon Gen 3 is an amazing notebook, we ordered ours with the 2560x1400 IPS screen and love it, still I don't see the value in uses such a fast drive in a glorified Office / travel Ultrabook. I want to use the SM951 for content creation and of course gaming! I want to use the drive paired with an 8-core processor (for content creation) and multiple video cards (gaming).

Luckily, like the XP941 last year, RamCity will stock Samsung's new SM951 PCIe 3.0 x4 SSD in all three available capacity sizes. RamCity is a valued member of the enthusiast community, and was started by people who understand and value enthusiast's requirements.

Specifications, Pricing and Availability

Samsung SM951 512GB M.2 PCIe SSD Review 03 |

At the SSD Global Summit, Samsung listed the SM951 as a 1TB product, but the specifications sheet only shows the product going up to 512GB. Samsung may have struck a deal to offer the 1TB model to a specific OEM, maybe one that is fruity, but we don't know at this time. Lenovo only offers the SM951 in 512GB at this time, as an undisclosed PCIe SSD.

The SM951 SSD specifications state the 512GB model is capable of 2150 MB/s sequential read and 1500 MB/s sequential write speeds. The random performance comes in at 90K read IOPS and 70K write IOPS. I will go ahead and tell you now that our results are quite a bit different.

Samsung SM951 512GB M.2 PCIe SSD Review 04 |

Using SiSoft Sandra 2015, we verified our SM951 was running on a PCIe 3.0 x4 (8Gbps) bus on an ASRock Z97 Extreme 6 motherboard. On this system, we only managed to achieve 1680 MB/s sequential read. This caused us some concern and we changed our test to mimic Samsung's test with a 128KB workload with a queue depth of 32. No matter what settings we changed, 1700ish was the maximum we managed to pull of the Lenovo X1 Carbon drive.

It's because of that we want to make it clear that our test today may not represent the full performance of the SM951 purchased from RamCity in the future. OEMs like Lenovo are able to order products in large volumes and at specific specifications. It is entirely possible that Lenovo limited the drive to reduce power consumption. Lenovo does have a slightly different part number, MZHPV512HDGL-000L1. The last section shows this is a Lenovo part. Units coming from RamCity will have 00000 or 000003 or 000001. We'll have to wait and see since no one commented from Samsung before we published this report.

On the other side of the coin, the SM951's random performance was not limited to the specifications 90K read IOPS and 70K write IOPS. In our test on a desktop system, we achieved over 180K random read IOPS and 106K random write IOPS. We will gladly trade a small amount of sequential performance for increased random performance. Unlike Samsung's retail consumer products, the OEM product specifications sheet does not list QD1 random read performance. This is an important metric for consumer SSDs because up to 70% of reads come from very low queue depth random workloads. In our tests, we found the SM951 reading QD1 random 4K data at over 12K IOPS, faster than any other consumer SSD available on the market today.

The SM951 also brings new innovations to power management. The drive is the first consumer storage device to use L1.2 power states for PCIe devices. In a roundabout way, you can think of this as the PCIe equivalent to DEVSLP for 2.5" consumer SSDs. Let's take a look at PCIe power states:

  • L0 - Active normal operating mode state.
  • L0s - Energy saving "standby" state with fast recovery back to L0.
  • L1 - Lower power "standby" state but with a longer recovery than L0s.
  • L2 - Auxiliary-powered deep-energy-saving state.
  • L3 - Link Off state.

The new power state on the SM951 pulls just 2mW. This will increase notebook battery life and also keep the new Samsung controller cool.

The new UBX controller is paired with Samsung's '10-nanometer class' 2D planar NAND. We suspect Samsung used the same 16nm MLC flash that also appeared on the 840 Pro, but at the same time, the model number does not list the same flash for both drives. The SM951 uses Samsung's fifth-generation flash, represented by the D, ten characters in from the start of the model name. The 840 Pro listed an A for the flash generation, but we don't have confirmation on what revision A represents. For OEMs, component cost is an issue. Using 3D V-NAND would increase the cost, even though the current price structure is a bit over the top.

We don't have specific pricing from RamCity at this time, but a good guess would be closer to $1 per GB at first with the larger capacity size coming in just under that mark and the smaller size a bit over. Again, this is speculation at this time, but we'll update the review to show pricing when we have it.

Last updated: Apr 7, 2020 at 12:33 pm CDT

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Chris Ramseyer started his career as a LAN Party organizer in Midwest USA. After working with several computer companies he was asked to join the team at The Adrenaline Vault by fellow Midwest LAN Party legend Sean Aikins. After a series of shake ups at AVault, Chris eventually took over as Editor-in-Chief before leaving to start Real World Entertainment. Look for Chris to bring his unique methods of testing Hard Disk Drives, Solid State Drives as well as RAID controller and NAS boxes to TweakTown as he looks to provide an accurate test bed to make your purchasing decisions easier.

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