Samsung 850 EVO review – putting 3D vertical NAND to the test

Reviews, Storage


I recently bought a Samsung 840 EVO on Amazon – a great deal at £90 for a 250GB solid state drive, or so I thought. A few days later, I was offered the chance to review the 850 EVO, and of course I couldn’t pass that up – especially as I now had the perfect means to see exactly what’s changed in the new generation.

The 850 Evo promises improved speeds and aggressive pricing thanks to its vertically stacked (3D) NAND. Today, we’ll find out if it’s a true improvement over the 840 series, or just marketing hype. Let’s go.


ControllerSamsung MGXSamsung MGXSamsung MGXSamsung MEX
DRAM Cache256MB512MB512MB1GB
Sequential Read540 MB/s540 MB/s540 MB/s540 MB/s
Sequential Write520 MB/s520 MB/s520 MB/s520 MB/s
Random Read940009700098000 IOPS98000 IOPS
Random Write880008800090000 IOPS90000 IOPS

Unboxing & Design


The Samsung 850 EVO comes in a pleasant white box, with the capacity marked and a proud ‘powered by 3D V-NAND Technology’ mention.


On the back, we have some assurances of “a new caliber of performance & endurance” and a nice “for review purpose only” sticker. Ooh, exclusive.


Inside the box, we find the SSD and the above – an installation guide, warranty statement and manual / driver CD.


Our first view of the SSD! It’s black, with Samsung written in white and Solid State Drive in grey. It’s the standard 2.5-inch size, of course.


The back is a little more exciting, showing various model numbers and regulatory information, as well as that 1TB capacity.


Finally, here’s a nice render of what the inside looks like.

That’s about it for design, so let’s move onto the fun part – testing!


As there’s little real-world analysis to be done, we’ll be strictly in benchmark land for the majority of this article. We’ll be testing the two Samsung drives – and a third Corsair drive, the most recent that I’ve tested – in a battery of tests to see which is the fastest. All drives are empty for the tests, and Windows is run on another SSD.

The test rig has a Core i7 2600K processor and 16GB of RAM; the OS is Windows 10. Note that Samsung’s RAPID caching was not used for these tests, as it doesn’t appear to support Windows 10.


Our two principle test subjects: two brand new Samsung SSDs, the 840 Evo and 850 Evo.


CrystalDiskMark has been one of my favourite benchmarks for evaluating storage speeds for a while now, thanks to its varied incompressible workload and extremely readable results. Here’s the 3.0.3 x64 version of the benchmark; all results are in MB/s.

CDM 3 ReadSeq512K4K4K QD32
Samsung 850 Evo51347238408
Samsung 840 Evo51547335397
Corsair Neutron GTX45037627328
CDM 3 WriteSeq512K4K4K QD32
Samsung 850 Evo50447968352
Samsung 840 Evo50039086313
Corsair Neutron GTX48046869158

In our first result, we see a fairly disappointing sign – the 850 provides only a marginal increase over the 840, with the only noticeable deltas coming in the 512K write test and 4K queue depth 32 test. Otherwise, the two drives are a stone’s throw from each other.

AS SSD Benchmark

AS SSD is another benchmarking tool quite similar to CrystalDiskMark, which uses predominantly incompressible data across a range of workloads including sequential tests, random performance and access times. First three numbers are MB/s and access time is in ms.

AS SSD ReadSeq4K4K QD64Acc. TimeScore
Samsung 850 Evo516343820.059467
Samsung 840 Evo513323300.059413
Corsair Neutron GTX507253340.068N/A
AS SSD WriteSeq4K4K QD64Acc. TimeScore
Samsung 850 Evo497662990.051415
Samsung 840 Evo497692070.054326
Corsair Neutron GTX473622950.062N/A

The biggest gains from the 840 to the 850 come in the higher queue depth sector, with the 850 recording scores 16% higher in the read test and 44% higher in the write test. Otherwise, the two drives are tough to separate, although both are better than the older Corsair drive.

ATTO Disk Benchmark

ATTO produces rather less comprehensible results than CrystalDiskMark, but still provides a good test of compressible data transfer. It also provides a lot of data points; I’ve selected six from across the range. Settings were the default: 256MB total length and queue depth of 4, testing from 1KB to 8MB. All results are in MB/s.

Atto Read1KB4KB64KB256KB1MB8MB
Samsung 850 Evo80269538551558558
Samsung 840 Evo94280535551555555
Corsair Neutron GTX1561336452530540
Atto Write1KB4KB64KB256KB1MB8MB
Samsung 850 Evo83255519529534534
Samsung 840 Evo81260515527533534
Corsair Neutron GTX15142474470493498

The two Samsung drives are near identical in these benchmark results, with the 840 taking a lead early on in the read test but losing out later on; in terms of write speeds the two drives are basically equivalent.

HD Tune Pro

We conclude with HD Tune Pro, a benchmark which produces three scores for average read speed, read access time, and burst read rate.

HD Tune Pro 5.50 ReadAverageAccess TimeBurst Rate
Samsung 850 Evo370 MB/s0.044 ms250 MB/s
Samsung 840 Evo358 MB/s0.041 ms231 MB/s
Corsair Neutron GTX340 MB/s0.059 ms231 MB/s

Here the Samsung 850 Evo shows its best results yet, with a small but noticeable lead in average read speed and burst read speed over its older brother.



While the Samsung 850 Evo proved both dependable and powerful across our battery of tests, I can’t help but be disappointed. I had expected a greater increase in performance from the new 3D NAND arrangement, instead of what amounts to marginal updates and even a few small regressions. While the difference in price is small, for the moment I’d advise that you go for the cheaper and more widely available 840 Evo models instead of these newcomers.


  • Consistently fast performance across all workloads
  • Low launch price, only ~20% more than the previous generation’s current price
  • Improved performance in high queue depth tests


  • Performance delta between 850 Evo and 840 Evo is small


  • 8 / 10

Last modified: December 8, 2014

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