Sequential Read Performance

Our first test of sequential read performance uses short bursts of 128MB, issued as 128kB operations with no queuing. The test averages performance across eight bursts for a total of 1GB of data transferred from a drive containing 16GB of data. Between each burst the drive is given enough idle time to keep the overall duty cycle at 20%.

Burst 128kB Sequential Read (Queue Depth 1)

The Samsung PM981 set new records for burst sequential read performance, but the Samsung 970 EVO fails to live up to that standard. The 970 EVO is a substantial improvement over the 960 EVO, but doesn't manage to beat the last generation's fastest MLC drives.

Our test of sustained sequential reads uses queue depths from 1 to 32, with the performance and power scores computed as the average of QD1, QD2 and QD4. Each queue depth is tested for up to one minute or 32GB transferred, from a drive containing 64GB of data.

Sustained 128kB Sequential Read

On the longer sequential read test, the Samsung 970 EVO performs far better than the Samsung PM981, indicating that Samsung has made significant firmware tweaks to improve how the drive handles the internal fragmentation left over from running the random I/O tests. The 970 EVO is the fastest TLC-based drive on this test, and the 1TB model even manages to beat the MLC-based 1TB 960 PRO.

Sustained 128kB Sequential Read (Power Efficiency)
Power Efficiency in MB/s/W Average Power in W

The 1TB 970 EVO draws more power during this sequential read test than any other M.2 drive in this mix, but its performance is high enough to leave it with a good efficiency score. The 500GB 970 EVO ends up with below-average efficiency.

Both capacities of the Samsung 970 EVO have very steady performance and power consumption across the duration of the sequential read test. This is in contrast to drives like the WD Black and Toshiba XG5 that don't reach full performance until the queue depths are rather high.

Sequential Write Performance

Our test of sequential write burst performance is structured identically to the sequential read burst performance test save for the direction of the data transfer. Each burst writes 128MB as 128kB operations issued at QD1, for a total of 1GB of data written to a drive containing 16GB of data.

Burst 128kB Sequential Write (Queue Depth 1)

The burst sequential write performance of the Samsung 970 EVO tops the charts, with the 500GB model almost reaching 2.5GB/s where the last generation of drives couldn't hit 2GB/s. The WD Black is only slightly behind the 970 EVO.

Our test of sustained sequential writes is structured identically to our sustained sequential read test, save for the direction of the data transfers. Queue depths range from 1 to 32 and each queue depth is tested for up to one minute or 32GB, followed by up to one minute of idle time for the drive to cool off and perform garbage collection. The test is confined to a 64GB span of the drive.

Sustained 128kB Sequential Write

On the longer sequential write test, the 1TB 970 EVO takes a clear lead over everything else, even the 1TB PM981. The 500GB model is handicapped by its smaller capacity and smaller SLC cache, but still manages to be significantly faster than the 512GB PM981.

Sustained 128kB Sequential Write (Power Efficiency)
Power Efficiency in MB/s/W Average Power in W

The 970 EVO and PM981 offer almost exactly the same power efficiency on the sequential write test. The 1TB model is slightly less efficient than the WD Black and 960 PRO, while the 500GB model is well behind the MLC-based drives of similar capacity.

The 1TB 970 EVO starts off with a much higher QD1 performance on the sequential write test than the PM981 offers, and at higher queue depths it maintains a slight lead. At 500GB, the 970 EVO's performance oscillates as only some portions of the test are hitting the SLC cache.

Random Performance Mixed Read/Write Performance


View All Comments

  • PeachNCream - Tuesday, April 24, 2018 - link

    That's a lot of "meh" in terms of performance for the high price. Reply
  • Samus - Wednesday, April 25, 2018 - link

    I agree. It's basically tied with the WD Black in real world performance, but the WD Black sells for $70 less (500GB) or 40% less. That's pretty ridiculous. Reply
  • Reppiks - Wednesday, April 25, 2018 - link

    The problem with Black is the naming, when I look in Danish shops they list 800MB/s writes so I presume thats an earlier generation? That makes it really hard to know what your buying when they dont have a WD Black 1gen, 2gen etc Reply
  • moozooh - Wednesday, April 25, 2018 - link

    > The problem with Black is the naming
    That's racist.™
  • jtd871 - Wednesday, April 25, 2018 - link

    I seriously can't tell if you're trying to sound clever or infantile. Reply
  • peevee - Monday, April 30, 2018 - link

    He is succeeding at being funny. You have to be in the US context to understand why. Reply
  • azrael- - Thursday, April 26, 2018 - link

    You need to look specifically for "NVMe" as the new WD Black SSDs are postfixed "NVMe" instead of "PCIe". For instance, a search on the ProShop site yielded five drives for "wd black nvme" of which the three were postfixed "NVMe". These are the new ones and they are *considerably* more expensive. At least a 54% markup over the old versions. Reply
  • FullmetalTitan - Wednesday, April 25, 2018 - link

    Not sure where you are getting those price differentials from. WD Black and 970 EVO MSRPs are matched for every shared capacity. Reply
  • peevee - Monday, April 30, 2018 - link

    newegg 1TB m.2 SSD prices:
    Crucial MX500 (SATA) $250
    HP EX920 (NVMe PCIe x4) $360
    Intel 760p (NVMe PCIe x4 )$400
    WD Black (NVMe PCIe x4) $450
    Samsung 970 EVO (NVMe PCIe x4) $600.
    960 PRO $609.

    Sams prices obviously need to CRASH before they make any sense.
  • Samus - Thursday, July 12, 2018 - link

    WD Black 512GB NVMe had regularly sold for $150 on sale. Until the Samsung price drops in May, the EVO 970 500GB never sold under $200, and was regularely $220-$230.

    So my statement is 100% factual and correct as of the time or writing on April 25, and as of now:

    "WD Black sells for $70 less (500GB) or 40% less"

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