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)
Orange is for the new drives, Blue is for the previous generation models

The burst sequential read speeds of almost all of these SATA drives are essentially equivalent; the slightly lower scores from the new WD and SanDisk drives are not a meaningful drop from the previous generation.

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 test of sequential reads, the WD Blue 3D NAND and SanDisk Ultra 3D end up in the second tier of SSDs, tied with the Intel 545s and Toshiba's MLC-based OCZ VX500, but Samsung's 850 PRO and 850 EVO still have a substantial performance advantage.

Sustained 128kB Sequential Read (Power Efficiency)

The power efficiency of the WD Blue 3D NAND and SanDisk Ultra 3D is excellent, trailing behind only the MLC-based OCZ VX500 that also uses a reduced amount of external DRAM. The previous generation of SanDisk and WD drives had the same power efficiency as Samsung's 850 PRO and EVO, which was good by last year's standards.

From QD1 to QD2, the WD Blue 3D NAND and SanDisk Ultra 3D see a slight improvement in sequential read performance and don't benefit any further from higher queue depths. The Samsung 850 PRO and 850 EVO both show a much larger jump in performance from QD1 to QD2, leading to a higher steady-state sequential read speed. The OCZ VX500 can actually match the Samsung drives at high queue depths, but it doesn't saturate until QD4.

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)

As with sequential reads, the burst sequential write speed of the new WD and SanDisk drives is slightly reduced from the preceding generation, but the performance isn't low enough to make the new drives stand out from the crowd.

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

The performance of the WD Blue 3D NAND and SanDisk Ultra 3D on the longer sequential write test is much improved from the previous generation of drives, but still rather slow compared to the competition.

Sustained 128kB Sequential Write (Power Efficiency)

With a substantial performance boost, the power efficiency of the latest WD/SanDisk SSDs is now about average, and is competitive with Samsung's drives but far lower than what the Crucial MX300 or OCZ VX500 offer.

The mediocre sustained sequential write performance of the new WD/SanDisk 3D NAND SSDs is due to a combination of relatively low performance once the drive has reached its full performance, and a slow ramp up that is still not quite at full speed by QD4. Most drives are operating at or very near their full performance at QD2.

Random Performance Mixed Read/Write Performance


View All Comments

  • Foeketijn - Thursday, September 14, 2017 - link

    We are talking about a Watt. Difference or so. Adding an extra fan has more impact. (Laptop? Who is upgrading a laptop with an 2,5" disk? Those are only found in really cheap devices anyway) The evo is known to just keep on going way way over that endurance point. How will these fare? We don't know yet. I think he has a fair point. There is no logical reason to choose this over a samsung other than not liking samsung. And samsung is just sitting there waiting till people notice their m2 driver are creaping to their sata prices. For a couple dollar more you get benchmarks that don't fit in these diagrams. I'm not a samsung fan. Just sad that no one is even trying to win this fight. The 850 evo is almost 3 years old and still on top for it's pricepoint (250Gb it is) Reply
  • mapesdhs - Thursday, September 14, 2017 - link

    Indeed, so until I see tech akin to the 850 EVO come back down to the 55 UKP level for 250GB where it was at a couple of years ago, I just keep hunting for new or lighly used 840 Pro or other models via normal auction, bagged another 840 Pro 256GB recently for 51 UKP; would be fascinating to see how this model and others from previous generations of good SSDs would fare in these tests (Vertex4, Neutron GTX, Extreme Pro, Vector, etc.) Except for power consumption (who cares in a desktop), I doubt the latest models are that much better at all. I miss the days of buying an 850 EVO 500GB for 118 UKP (that was Oct/2015).

    Until then, there's better value in NVMe models with addin card adapters, eg. SM951.
  • Luckz - Wednesday, October 11, 2017 - link

    When talking pound prices, it might be reasonable to mention how much your currency has changed since the 840 came out. Reply
  • Rictorhell - Thursday, September 14, 2017 - link

    Hoping for someone, other than Samsung, to come up with a viable and somewhat affordable 4tb ssd, sata, or otherwise, so that prices at or near that capacity will become at least somewhat reasonable, someday, for those of us that need/want that capacity in an ssd. Reply
  • MajGenRelativity - Thursday, September 14, 2017 - link

    That would be nice, but for now, you could just buy two SSDs and RAID them together? Reply
  • mapesdhs - Thursday, September 14, 2017 - link

    That's one heck of a reliability risk. Reply
  • MajGenRelativity - Friday, September 15, 2017 - link

    Depending on the RAID type, your reliability risk would be the same, or better. Could be worse, but that would be if you were doing a striped volume, which only increases performance, and I don't think OP was looking for that Reply
  • CheapSushi - Sunday, September 17, 2017 - link

    Yeah, so is having 1 PSU, no redundant power from difference sources, so is not having ECC RAM usually because anyone that does something with their computer is looking for six nines in uptime because they're obviously a datacenter... Reply
  • TheinsanegamerN - Sunday, September 17, 2017 - link

    So is keeping 4TB of data on a single drive that can fail without warning. Reply
  • BrokenCrayons - Thursday, September 14, 2017 - link

    Nice drives for a reasonable price and finally Samsung is starting to see a few competitive products but I don't think the focus is on SATA SSDs at this point. They're commonplace, but because the drive interface is limiting performance, we're unlikely to see any further high performance storage products for SATA which may explain why Samsung's not fighting very hard to keep a top tier drive there. They need mainstream and/or cost-effective storage which are essentially what SanDisk/WD, Crucial, and every other company that sells SATA SSDs ships out now. There's nothing wrong with that situation. I'm still on SATA and perfectly happy with the product selection out there now, but there's not much envelope left to push without shifting to interfaces like NVMe. Reply

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