Samsung SM951 PCIe M.2 512GB SSD Review

Why you can trust Tom's Hardware Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.

Notebook Battery Life

I take a different approach to testing SSD power consumption. As end users, we never just read data or write data to our drives. Even if we did, power consumption varies based on the workload we apply. After a write takes place, the SSD consumes additional power to execute background tasks like garbage collection, TRIM and wear leveling. An SSD that consumes X watts while processing sequential data, Y watts processing random data and Z watts at idle might not facilitate better notebook battery life compared to another product found to use more power in those same tasks. Rather than looking at numbers of nearly insignificant value, we want to present the big picture.

There's a fourth drive in the above chart to help us make our point. With the SATA-based MyDigitalSSD SBe 120GB included, we see that there isn't a battery life advantage to using PCIe or SATA at this time. In fact, the SATA drive technically outperforms the three PCIe-based devices.

Samsung's SM951 delivers  slightly more longevity than the older XP941. And both Samsung SSDs outshine Plextor's M6e Black Edition 512GB. With that said, Plextor sells the M6e Black Edition in a M.2-to-PCIe adapter, so it's not optimized for notebook use.

When you pull the power plug on your notebook, Windows changes power schemes to reduce power consumption. The CPU, memory, DMI, SATA and PCIe buses slow down in response. In some systems, the cooling fans are even spun down.

Naturally, in this state, performance is reduced. With that in mind, we can still measure SSD efficiency in a low-power environment. The rating we're reporting covers the entire platform. But the only variable changing between tests is the SSD. Samsung's SM951 and XP941 drives deliver the highest performance ratings in this power state.

Chris Ramseyer
Chris Ramseyer is a Contributing Editor for Tom's Hardware US. He tests and reviews consumer storage.
  • blackmagnum
    This is an awesome upgrade for some Macbook Air/Pro users, but just wait until Intel shows their product... and will there be any hardware compatibility issues with DIY upgrades?
  • Sakkura
    I'm disappointed the promised NVMe support did not materialize. But I guess Samsung is saving that for later retail products. Can't argue with the performance though, this is by far the fastest consumer SSD around.
  • Memory Ever
    May I know the model and nae of the PCIe adapter you used in the tests???
    No 1TB edition? Fail.
  • tom10167
    I wish they'd put an 840 or 850 pro in the comparison just to give us a better sense of scale. This drive is incredible, though, and $550 for a 512GB cutting edge drive is not terrible!
  • mapesdhs
    The Power Restricted Performance graph is stupid. Please stopping using
    graphs with origins that don't start at zero - the visual graphic impact is
    totally meaningless.


  • jeffunit
    You might want to fix the labels of your graphs. Latency in seconds? One chart shows a write speed of about 80 gigabytes per second.
  • liquidpower
    I also wished they put a 850 pro in the charts to see the jump from the fastest sata to the PCIe-based M.2
  • maestro0428
    You can purchase these at in the Enterprise SSD section. I want one!
  • generalsheep
    Is this little bastard bootable,so i can use it as my maindrive?