Samsung 840 Pro 256GB SSD Review

In the enthusiast SSD market two products stand taller than the rest - the OCZ Vector and Samsung's 840 Pro. Today we're looking at the 256GB capacity size. Two drives enter, one drive leaves the champion.

Manufacturer: Samsung
14 minutes & 52 seconds read time


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The top performance tier of any market is a fascinating place. Performance in just about any task provides a clear point of reference to judge a product. The very best products tend to cost more than those further down the list and because of that, the very best products are not the most consumed.

Determining what products is the fastest is just one way to measure SSDs. Price and performance tend to get most of our attention here at TweakTown, but other factors, such as reliability and availability do factor in when we write a review.

In 2012, three products stood out as delivering the highest performance possible for the SATA III interface. SuperSSpeed's S301 SLC SSD has dropped off that list for today's review because the architecture doesn't support capacity sizes over 128GB. The price would also be an issue if it did as well. OCZ's Vector and Samsung's 840 Pro on the other hand are left and both products scale to 512GB.

We've reviewed the OCZ Vector SSD in all three capacity sizes, the only review site that I know of to do so. Samsung has been a tough nut for us to crack and I'm sure there are a few reasons why. One that comes to mind is our reluctance to recommend Samsung's lower capacity products. We didn't like the 830 128GB nor the 840 Pro 128GB. Samsung's architecture produces strange latency results in the lower capacity sizes in some of our tests, and you can feel the latency under real-world use.

Just because Samsung doesn't seed us with their products, it doesn't mean we're not going to review them. That said, we acquired our own 840 Pro 256GB drive and shall beat it to a pulp today just like any other SSD. 840 Pro is a product most of our readers want to see because our readers tend to purchase higher end SSDs.

Specifications, Pricing and Availability

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Samsung released the 840 Pro in three capacity sizes - 128GB, 256GB and 512GB. We've already looked at the 128GB model around a month ago and plan to scale to the 512GB over time. Today we're putting the 256GB drive through the ringer.

Samsung does a good job providing performance data to end users on their webpage. The 256GB rates at 540MB/s sequential read, 520MB/s sequential write. IOPS performance is very impressive, up to 100K IOPS random read and 90K IOPS random write speed. Samsung does not go into any detail at all about their NAND. We would really like to know the program erase cycles, but at this time Samsung doesn't provide any details at all other than it's MLC on the 840 Pro and TLC on the 840.

Samsung's 840 and 840 Pro ships in 7mm z-height, a nice feature since many ultrabooks on the market use either mSATA or 7mm 2.5" form factors.

Samsung backs the 840 Pro with a five year warranty. After looking at Newegg we found only a handful of single and two star ratings for the 840 Pro 256GB, a good indication that the product is reliable, most of the star ratings were five or four with excellent feedback. Newegg shows the 256GB drive at $249.99 at the time of writing. That price also includes free two day shipping.

The 840 Pro product line uses the same Samsung Magician Software as the 840. The same software package also rolls over to the Pro line with data migration software included in the bundle. We covered the software in the 840 500GB review last month.


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The 840 Pro ships in a very nice package with a lot of color. A sticker on the front lists the capacity size.

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On the back we found specific performance information and some detailed information about the controller, DRAM buffer and encryption engine.

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Inside we found a well-put together package with all paper manuals and software disk tucked under the drive carrier.

Samsung 840 Pro 256GB SSD

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Unlike the 830, Samsung now uses an all metal case for the 840 and 840 Pro.

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On the outside, there isn't much to distinguish the 840 from the 840 Pro other than the label on the back of the drive.

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The 7mm design is essential for all new SSDs since the market is pushing this new form-factor to produce smaller and lighter designs. Even if you don't need a 7mm drive today, you will in the future.

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The 7mm spec doesn't change the location of the mounting points or SATA power and data cable.

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The Samsung 840 Pro uses a three-core controller. Each core handles a different task - one for reading, one for writing and a third to perform background tasks.

Samsung doesn't need to source any of the major components from other suppliers. They make the DRAM, controller and NAND flash.

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All eight NAND flash chips are on the top side of the PCB. This side is void of all surface mount components.

Benchmarks - Test System Setup and ATTO Baseline Performance

Desktop Test System

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Lenovo W530 - Mobile Workstation

We use two systems for SSD testing. The desktop runs a majority of the tests and the Lenovo W530 runs the notebook power tests as well as the real-world file transfer benchmark.

ATTO Baseline Performance

Version and / or Patch Used: 2.34

ATTO is used by many disk manufacturers to determine the read and write speeds that will be presented to customers.

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In ATTO we were just shy of 560MB/s when reading data off of the Samsung 840 Pro. Writing data occurred at 518MB/s. The performance was in line with Samsung's specification numbers.

Benchmarks - Sequential Performance

HD Tune Pro

Version and / or Patch Used: 4.00

Developer Homepage:

Product Homepage:

HD Tune is a Hard Disk utility which has the following functions:

Benchmark: measures the performance

Info: shows detailed information

Health: checks the health status by using SMART

Error Scan: scans the surface for errors

Temperature display

HD Tune Pro gives us accurate read, write and access time results and for the last couple of years has gained popularity amongst reviewers. It is now considered a must have application for storage device testing.

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Both the 840 and 840 Pro do very well when reading sequential data at QD1. Vector limits QD1 reads to around 350MB/s, but when the commands are stacked, the performance increases to around 500MB/s. The 840 and 840 Pro also increase performance when the queue depth is increased. We'll see higher NCQ writes in the CrystalDiskMark tests later in this review.

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Here we see one of the large differences between the base 840 and the 840 Pro - write performance. The 840 Pro with MLC NAND writes much faster than the 840 with TLC. In this test using 64K size data, Vector enters 'storage mode' and slows halfway through the test. The low minimum speed isn't something you'll hit under normal use, but it does show up in our testing.

HD Tach - Sequential Write Performance After Random Writes

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The Samsung 840 Pro still writes sequential data at an average speed of 395MB/s after being hit with a large amount of random writes. This is much better than the 840 Pro 128GB and 840 250GB.

Benchmarks - AIDA64 Random Access Time

AIDA64 Random Access Time

Version and / or Patch Used: 1.60

Developer Homepage:

Product Homepage:

AIDA64 offers several different benchmarks for testing and optimizing your system or network. The Random Access test is one of very few if not only that will measure hard drives random access times in hundredths of milliseconds as oppose to tens of milliseconds.

Drives with only one or two tests displayed in the write test mean that they have failed the test and their Maximum and possibly their Average Scores were very high after the cache fills. This usually happens only with controllers manufactured by Jmicron..

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The Samsung 840 Pro holds a steady .07ms line on our chart, the same as 840 and Vector.

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Even with a DRAM buffer for page data, the 840 Pro struggles to keep latency down through the entire run. This was our biggest complaint with the 128GB 840 Pro.

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Here we see the actual run in the test. For 71% of the test the drive is fine with a very low .07ms write latency. At 72% the latency spikes and hovers in the .15 to .2 range. The difference between the 256GB drive and the 128GB drive is the 71% that you can write to before the drive cleans itself up which adds latency to your activity.

Benchmarks - Anvil Storage Utilities

Anvil Storage Utilities

Version and / or Patch Used: RC6

So what is Anvil Storage Utilities? First of all, it's a storage benchmark for SSDs and HDDs where you can check and monitor your performance. The Standard Storage Benchmark performs a series of tests, you can run a full test or just the read or the write test or you can run a single test, i.e. 4K DQ16.

Anvil Storage Utilities is not officially available yet but we've been playing with the beta for several months now. The author, Anvil on several international forums has been updating the software steadily and is adding new features every couple of months.

The software is used several different ways and to show different aspects for each drive. We've chosen to use this software to show the performance of a drive with two different data sets. The first is with compressible data and the second data set is incompressible data. Several users have requested this data in our SSD reviews.

0-Fill Compressible Data

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Incompressible Data

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The 840 Pro lost a little performance when working with 100% incompressible data (coming from compressible). The largest drop off came when writing sequential data.

Read IOPS through Queue Depth Scale

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With the upper limits of SATA III reached nearly two years ago, both Samsung and OCZ turned to IOPS performance in their marketing material. Both companies spout on about 100K IOPS this and 100K IOPS that, but most of us rarely use anything higher than a queue depth of 8. Even getting to QD8 means heavy multitasking is taking place, but QD1, 2 and 4 are pretty common.

When it comes to read IOPS at low queue depths the Samsung 840 Pro 256GB just has more get up and go when compared to Vector 256GB. This is an important test for every type of users, especially people like me that build near supercomputers and then end up surfing the web more than anything else. Since this is read IOPS, disk intense apps like games (loading the files into RAM and start up), Photoshop (mainly startup) or for that matter just about any Adobe software will load faster with 840 Pro. The difference is not much, but as you'll see in this review these two drives are evenly matched.

Scaling Write IOPS through Queue Scale

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That said, when it comes to writing small files, we see Vector has a bit of a lead here but again, not by much in this capacity size.

Benchmarks - CrystalDiskMark


Version and / or Patch Used: 3.0 Technical Preview

Developer Homepage:

Product Homepage:

Download here:

CrystalDiskMark is a disk benchmark software that allows us to benchmark 4K and 4K queue depths with accuracy.

Key Features:-

* Sequential reads/writes

* Random 4KB/512KB reads/writes

* Text copy

* Change dialog design

* internationalization (i18n)

Note: Crystal Disk Mark 3.0 Technical Preview was used for these tests since it offers the ability to measure native command queuing at 4 and 32.

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Here we see those 4K read IOPS put to the test and a measurement displayed at throughput. 840 Pro 250GB writes 4K data at 40MB/s and Vector 256GB does it at 31MB/s. Both drives scale well through the queue depth tests, but Samsung has a lead.

Here we also get our first look at sequential reads at higher than QD1. Again, Samsung has a lead here, not by much, but a lead nevertheless. The difference is Vector limits a single request to just 350MB/s so you have a reserve for multitasking. When we first tested Vertex 4 the QD1 read limit was just 200MB/s, an imposed limit that hampered file transfers especially large sequential transfer like movies. The limit was increased with later firmware. Let's discuss this late in the review when we talk about real-world file transfers.

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As we discussed on the previous page, Vector has a little extra umph when writing 4K data. The Samsung 840 Pro's 4K write performance isn't anything to overlook though since 135MB/s is still higher than most of the products on our chart.

Benchmarks - PCMark Vantage Hard Disk Tests

PCMark Vantage - Hard Disk Tests

Version and / or Patch Used: 1.0.0

Developer Homepage:

Product Homepage:

Buy It Here

PCMark Vantage is the first objective hardware performance benchmark for PCs running 32 and 64 bit versions of Microsoft Windows Vista. PCMark Vantage is perfectly suited for benchmarking any type of Microsoft Windows Vista PC from multimedia home entertainment systems and laptops to dedicated workstations and high-end gaming rigs. Regardless of whether the benchmarker is an artist or an IT Professional, PCMark Vantage shows the user where their system soars or falls flat, and how to get the most performance possible out of their hardware. PCMark Vantage is easy enough for even the most casual enthusiast to use yet supports in-depth, professional industry grade testing.

FutureMark has developed a good set of hard disk tests for their PCMark Vantage Suite. Windows users can count on Vantage to show them how a drive will perform in normal day to day usage scenarios. For most users these are the tests that matter since many of the old hat ways to measure performance have become ineffective to measure true Windows performance.

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HDD1 - Windows Defender

HDD2 - Gaming

HDD3 - Windows Photo Gallery

HDD4 - Vista Startup

HDD5 - Windows Movie Maker

HDD6 - Windows Media Center

HDD7 - Windows Media Player

HDD8 - Application Loading

With 840 Pro 256GB faster at reading data and Vector 256GB faster at writing data, it doesn't surprise me to see these two drives going back and forth in our simulation of real-world, daily use activity tests.

With performance this close it really comes down to preference because you aren't going to see most of these differences in your notebook or desktop.

Benchmarks - PCMark Vantage - Drives with Data Testing

For a complete breakdown on the Drives with Data Testing please read this article. You will be able to perform this test at home with the files provided in the article - full instructions are included.

- Brief Methodology

SSDs perform differently when used for a period of time and when data is already present on the drive. The purpose of the Drives with Data testing is to show how a drive performs in these 'dirty' states. SSDs also need time to recover, either with TRIM or onboard garbage collection methods.

Drives with Data Testing - 25%, 50%, 75% Full States and Dirty / Empty Test

Files needed for 60 (64GB), 120 (128GB), 240 (256GB)

60GB Fill - 15GB, 30GB, 45GB

120GB Fill - 30GB, 60GB, 90GB

240GB Fill - 60GB, 120GB, 160GB

Empty but Dirty - a test run just after the fill tests and shows if a drive needs time to recover or if performance is instantly restored.

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The tiebreaker really comes right here, how do these two drives, the fastest consumer 256GB models in the world, perform when data is on the flash. The Samsung 840 Pro 256GB is faster than Vector when both drives are half-full with the same data.

CrystalDiskMark - Boot Drive, 206GB Data on Drive

Samsung 840 Pro 256GB with 206GB Data on Drive:

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OCZ Vector 256GB with 206GB Data on Drive:

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We've never shown this test before in a published article, but we have data for every SSD we've tested going back five months. A handful of tests are run when we add data to the drive in our Lenovo W530. The drives filled with control data until only 50GB of capacity remains on the test drive. This is also how we get the 50GB free Time to Windows Boot Test results as well.

These two images show what happens when we add data to an SSD.

Benchmarks - BootRacer

BootRacer - System Boot Time

Version and / or Patch Used: 4.0

Developer Homepage: Greatis

Product Homepage: BootRacer

Download here:

Note: In this test we use the Lenovo W530 Mobile Workstation loaded with an operating system and several program files. The data on the drive at the time of the test is 45GB. The second test, 50GB Free, was run with the drives filled with block data until only 50GB of free capacity remained.

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Speaking of our time to Windows Boot Test, here we see that Vector makes into Windows just a little faster than 840 Pro, at least in this capacity size. The difference is less than a second and without a stopwatch (or this special program), you won't see a difference.

Benchmarks - DiskBench

DiskBench - Directory Copy

Version and / or Patch Used:

Developer Homepage: Nodesoft

Product Homepage: DiskBench

Download here:

Note: In this test we use the Lenovo W530 Mobile Workstation and a SuperSSpeed S301 SLC 128GB SSD to move a 15GB block of data to and from the target drive. This is part of our real world test regiment. Roughly 45GB of data resides on the target drive before the '15GB Block' is transfer. The 15GB Block is the same data we built for the Data on Disk Testing and is a mix of compressible and incompressible data.

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Earlier in the review, I said we would expand on file transfers a little more. As you can see on the chart none of the drives make it past 310MB/s reading or writing data. This is a limit imposed by the Windows file system for the most part. Granted, you can get higher results with RAID arrays, but for everything over 300, you have to give a little back to Windows, the processor, the chipset and so on.

What this means for you is Vector's QD1 limit of 350MB/s and 840 Pro's maximum performance with the file system of 460ish MB/s still gives you around 300MB/s when transferring data. I know right, sometimes life just isn't fair.

Benchmarks - Power Testing

Bapco MobileMark 2012 1.5

Version and / or Patch Used: 2012 1.5

Developer Homepage:

Test Homepage:

MobileMark 2012 1.5 is an application-based benchmark that reflects usage patterns of business users in the areas of office productivity, media creation and media consumption. Unlike benchmarks that only measure battery life, MobileMark 2012 measures battery life and performance simultaneously, showing how well a system design addresses the inherent tradeoffs between performance and power management.

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Our test notebook hasn't been optimized to run for ten hours, we did this to reduce the time needed to run this test. In our test, the Samsung 840 Pro delivered around 10 extra minutes of battery life over Vector. The 840 delivered nearly 20 more minutes over the 840 Pro.

PCMark Vantage HDD Test - Power Draw

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Here we see where the extra battery time came from. Samsung's 840 class drives use far less power at idle than Vector, an important feature for notebook users since most of the time your SSD is idle.

The idle time is where Samsung has an advantage, but with just these three drives on the chart, we see that Vector actually uses less power when active. In consumer tests this isn't all that important, but in enterprise tests were drives are busy more than they are idle, it might be enough to shatter Samsung's presumed lead as the low power leader.

Final Thoughts

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Not long ago we published our 840 Pro 128GB review and compared it heavily to OCZ's Vector 128GB. In that review we gave a solid thumbs up to Vector in that capacity size. When it comes to the 256GB capacity size things are quite a bit different. Here the nod goes to Samsung and the 840 Pro.

To break it all down let's look at the price first. Vector is $269 and 840 Pro is $249, a difference of $20. It isn't a whole lot, but it's enough to make a judgment on. Both of these drives were very close in our standard SSD review tests so to break the tie we pulled a new test out of our NAS server - advanced fill testing. When we looked at each of these drives, both filled with 206GB of data on them, 840 Pro was the clear winner. I guess you could call it overtime but extended play or not, 840 Pro 256GB is faster when it needed to be... but there is still a last shot of hope for Vector and it's only there because Samsung left the door open.

Desktop users only apply to this - OCZ includes a desktop adapter bracket, a nice plus if your case doesn't have a native 2.5" drive bay. Looking at the accessory package, both drives have a five year warranty, both include data migration software, both have easy firmware updates, but Samsung's software does cover more automated tasks than OCZ's. For desktop users, the adapter bracket is nice.

Notebook users, you care about power, I know... I'm on a notebook more than any other computer in the house. The ten extra minutes in my test scales when your notebook delivers more than 300 minutes (five hours) of battery power. We use a 6-cell battery because donating five hours to one test is already extreme. If you use a 9-cell battery or a 10-hour ultrabook those ten minutes will scale to a larger margin of victory for the 840 Pro. The difference could be as high as an hour with a power-optimized notebook, 11 hours instead of 10. For notebook users the extra battery time is just as important as a desktop adapter bracket for desktop users.

The fastest 256GB consumer SSD on the market goes to the 840 Pro. In a couple of weeks we'll compare the 512GB models and do this all over again. Who knows, we may have something even faster in as well by that time from another company.

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