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Solid-state drives Reviews
15,670 Reviews

Samsung 840 Series 250GB review

£140 inc VAT

Manufacturer: Samsung

Our Rating: We rate this 4 out of 5

Samsung's 840 Series is the cheaper version of the Samsung 840 Pro Series, using the latest lower-cost TLC flash chips to keep the price down while still taking many of the performance features of the Pro product.

Samsung may have been a little late to the solid-state drive upgrade party, but it’s made quite an impression in the expanding market in only three or four generations of its SSD.

See also: Group test: what's the best SSD (solid-state drive)?

The Korean semiconductor specialist had long experience with flash and controller chips of course. But it wasn’t until first the Samsung 470 Series and then 2011’s Samsung 830 Series that it really targeted consumer retail directly, rather than selling its silicon wares to other brands to repackage and sell.

The latest Samsung 840 Series is pitching in to the mêlée of fast storage more aggressively than ever before, with two distinct models of varying capacities each. These are the standard 840 and the 840 Pro, aimed at the popular entry-level and the enthusiast/power-user audience respectively.

In the case of the regular 840 Series SSD here, it’s the first time that we’ve seen a new type of flash storage, one that uses not two but three stacked layers of memory cells. 

To recap on the types of flash, the original NAND flash chips used single-layer cell (SLC) technology which offers excellent write performance and good longevity.

Then came multi-layer cell (MLC), although this is best known as just two layers stacked. This allowed larger capacities and lower prices, at the expense of slightly slower write speed and shorter overall lifespans.

But the Samsung 840 Series has three-layer cell (TLC) technology, allowing further reductions in price but also adding a question mark over longer-term longevity: it’s believed that TLC storage may not have the staying power of even MLC. Samsung backs this version of the 840 Series with a three-year warranty.

The storage capacities available are subtly different to the norm for solid-state technology. Usually, SSDs follow binary computing sizes, such as 64, 128, 256 and 512GB. But as with SSDs using SandForce controllers, Samsung has engineered in extra over-provisioning, leaving some spare capacity for internal housekeeping and to maintain capacity after areas of the drive become unwritable with age.

Capacities offered for the Samsung 840 Series are 120GB, 250GB and 500GB. We tested the 250GB version, which presents as 232GB available space in Windows.

To help the data transfer process for Windows users, Samsung offers its Data Migration Tool software that can help copy an old Windows C drive across to a newly installed Samsung SSD.

At the new drives’ press launch Samsung told us that it wants to address and sell to a ‘much wider demographic, and make it easy for all of our customers’. That’s a very laudable plan, to help bring the undeniable benefits of solid-state storage to a wider audience of personal computer users.

Partly fullfilling this aim is the Samsung SSD Magician software for Windows. This all-in-one utility is said to allow you to, among other things, test performance, adjust over-provisioning and update firmware. Samsung’s allegiance to Microsoft-based computing is exclusive though – if you do not use Windows, Samsung does not support you with any of the facilities offered by this tool.

While the performance-test part of the Magician utility worked fine, we had issues with the firmware upgrade. The tool reported that our test drives were up-to-date, even when they were not. This was later corrected in late December 2012, with the now-latest firmware for this model of DXT07B0Q finally made available online.

This is a welcome turnaround from the company’s former stated position. At the international press conference for the launch of the new products, a Samsung spokesman told us that the company’s approach is not to let the customer update their drives ‘because we make SSDs so good they don’t need any updates’.

Samsung 840 Series 250GB: Performance

Our first lab test quickly established the Samsung 840 Series’ sequential read credentials. With the help of the current-standard SATA 6Gbps interface, the 840 showed read speeds up to 560MBps in the ATTO benchmark test.

In fact, it’s drives like this that are showing the limitations of the SATA standard, highlighting the need for its replacement, likely to be the PCI-E-based next-generation form factor (NGFF) standard that may become available in 2013.

Write speeds were much lower, and in line with Samsung’s printed specification of ‘up to 250MBps’.

Here we saw a maximum speed of 263MBps. While less than half the drive’s read speed, it was as expected from the new TLC flash technology, which is known to have 50% slower latency due to the added complexity in program/erase (PE) writing to deeper buried cells.

CrystalDiskMark demonstrated little difference in sequential speeds between compressible and incompressible data, a worthy asset not found with the popular SandForce-based solid-state drives. This means that media files like MPEG and JPEG will be written at the same speed as other file types.

Headline speeds with CDM were 509MBps read and 256MBps write. In the small file tests, we did see small differences. For example, 30MBps was the result when reading 4kB zeroes or ones; but 22MBps for random data.

In the AS SSD test, we saw similar numbers overall. Sequential reads and writes were at 519 and 251MBps, and 4kB read/writes at 19/75MBps. With stacked-up data the Samsung performed very well, hitting 290MBps and 209MBps in the 64-thread 4kB test, reads and writes respectively. 

Translated into IOPS numbers, the Samsung 840 measured 74k IOPS for reads and 53k IOPS for writes in the AS SSD benchmark.

These are great results for an SSD at this highly attractive price, and should translate into great real-world performance to make for a highly responsive PC.

Samsung 840 Series 250GB Expert Verdict »


Samsung SSD 840 250GB reviews verified by Reevoo

Samsung SSD 840 250GBScores 9.0 out of 10 based on 322 reviews
250GB solid-state drive
2.5in form-factor
SATA 6Gbps
512MB DDR2 cache
Samsung 3-core MDX controller (ARM Cortex R4F
21nm Toggle-Mode 2.0 NAND flash
TRIM support
auto garbage collection algorithm
100 x 70 x 6.5mm
53g
3-year warranty
  • Build Quality: We give this item 8 of 10 for build quality
  • Features: We give this item 7 of 10 for features
  • Value for Money: We give this item 8 of 10 for value for money
  • Performance: We give this item 8 of 10 for performance
  • Overall: We give this item 8 of 10 overall

We have misgivings about the complete dearth of support outside Microsoft Windows, particularly now that Samsung’s SSDs are proving popular upgrades for Apple Mac computers where they're known to work so well. We cannot comment on longevity of the new technology yet but in terms of performance today, the Samsung 840 Series offers state-of-the-art SSD sequential read speeds, and decent small file juggling capability, the key to keep a fast-feeling and responsive computer.


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