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.


Capacity 120GB 250GB 500GB 1TB
Controller Samsung MGX Samsung MGX Samsung MGX Samsung MEX
DRAM Cache 256MB 512MB 512MB 1GB
Sequential Read 540 MB/s 540 MB/s 540 MB/s 540 MB/s
Sequential Write 520 MB/s 520 MB/s 520 MB/s 520 MB/s
Random Read 94000 97000 98000 IOPS 98000 IOPS
Random Write 88000 88000 90000 IOPS 90000 IOPS
Price £73.49 £109.99 £198.49 £367.49

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 Read Seq 512K 4K 4K QD32
Samsung 850 Evo 513 472 38 408
Samsung 840 Evo 515 473 35 397
Corsair Neutron GTX 450 376 27 328
CDM 3 Write Seq 512K 4K 4K QD32
Samsung 850 Evo 504 479 68 352
Samsung 840 Evo 500 390 86 313
Corsair Neutron GTX 480 468 69 158

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 Read Seq 4K 4K QD64 Acc. Time Score
Samsung 850 Evo 516 34 382 0.059 467
Samsung 840 Evo 513 32 330 0.059 413
Corsair Neutron GTX 507 25 334 0.068 N/A
AS SSD Write Seq 4K 4K QD64 Acc. Time Score
Samsung 850 Evo 497 66 299 0.051 415
Samsung 840 Evo 497 69 207 0.054 326
Corsair Neutron GTX 473 62 295 0.062 N/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 Read 1KB 4KB 64KB 256KB 1MB 8MB
Samsung 850 Evo 80 269 538 551 558 558
Samsung 840 Evo 94 280 535 551 555 555
Corsair Neutron GTX 15 61 336 452 530 540
Atto Write 1KB 4KB 64KB 256KB 1MB 8MB
Samsung 850 Evo 83 255 519 529 534 534
Samsung 840 Evo 81 260 515 527 533 534
Corsair Neutron GTX 15 142 474 470 493 498

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 Read Average Access Time Burst Rate
Samsung 850 Evo 370 MB/s 0.044 ms 250 MB/s
Samsung 840 Evo 358 MB/s 0.041 ms 231 MB/s
Corsair Neutron GTX 340 MB/s 0.059 ms 231 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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