Although the 840 is packaged in the familiar 2.5-inch form factor, Samsung opted for the slimmest of chassis which measures just 7mm in height. We were also a little taken aback at how light the drive was; it’s just 53.5 grams and feels like it might float away if you don’t hang onto it. The black (or is it a deep gray?) chassis is all metal with a slick-looking silver band around the edge.

The 250GB 840 has a SATA 6Gbps interface and is rated for sustained sequential read/write speeds of up to 540 MB/s and 250MB/s with up to 95,000/62,000 read/write IOPS. There’s 512MB of Samsung LPDDR2 SDRAM cache on board, as well as a 3-core Samsung MDX controller and Samsung Toggle DDR 2.0 NAND flash memory.

Looking at the PCB, you can see that it’s neat and tidy. There are 8 NAND modules on board, and all of them are on the top side and pasted in a tight, clean grouping. There’s really nothing at all on the underside of the PCB.

Samsung included wear-leveling and auto garbage collection in the 840 Series, as well as AES 256-bit encryption, TRIM support, S.M.A.R.T. support, and WWN support. The 840 SSD also comes with some free software in the form of Samsung SmartMigration and Samsung Magician.


Samsung Magician is surprisingly feature-packed and includes handy system information and links to sites with user guides and manuals, in addition to a firmware updater; performance optimization tools; OS optimization tools; and secure erase, over-provisioning, and disk clone features.


In addition to the software, the 840 comes with the boilerplate documentation as well as a 3.5-inch mounting bracket with screws and a USB-to-SATA/SATA power adapter so you can connect the SSD externally to pretty much any computer with a USB port.

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First, we ran SiSoft SANDRA, the the System ANalyzer, Diagnostic and Reporting Assistant. Here, we used the Physical Disk test suite and provided the results from our comparison SSDs. The benchmarks were run without formatting and read and write performance metrics are detailed below.

The SANDRA Physical Disk test plays well to the Samsung 840’s read throughput, as it posted the strongest score of the bunch. However, you can see that its overall performance is hampered by a weak write score, which is actually the lowest score in the whole field.

Following what we saw in the SANDRA test, this SSD’s read score is far better than its write score in ATTO, both relative to itself and to the entire test bank. While the Samsung 840 posted nice numbers in the write test with the smallest transfer sizes--second only to the OCZ Vertex 4--it planed out hard right at the 4KB transfer size mark and stayed there, where it ended up with the lowest score most of the rest of the way out.

On the other hand with respect to read performance, the Samsung 840 cleaned up, starting out incredibly strong and maintaining the top throughput for the entire read test.

The Samsung 840 SSD performed solidly in HD Tune for the most part. In the average transfer rate test, it scored within 30-40Mbps of the leaders while once again posting the weakest write score. Access time is apparently a strength of the Samsung 840, as it delivered the best write score of the group (although its read score wasn't as impressive here).

The 840 looked good in terms of CPU usage, delivering write performance that nearly matched the best score in the field and read performance that was right in the middle of the pack. Where this SSD performed best was in the burst rate test, which finally showed some parity in the drive's read and write scores; even better, the 840 was solidly in the lead pack compared to our other test drives.

Overall, the Samsung 840 did very well in our CrystalDiskMark tests. Again we see, in the sequential and 512K transfer tests, that this drive posts strong read scores and less impressive write scores; in both, it scored at the top in the former and at the bottom in the latter. In the 4K QD32 test, however, that write score came up significantly.

While the 840's read score in the 4K transfer test was solid, it was actually the write score that topped the charts for a change.

The PCMark 7 scores are for the most part completely uninteresting, which speaks well of all of the drives we’ve tested. The scores are clustered very tightly across the board, although it’s worth mentioning that the Samsung 840 is often at or near the top score in most of these tests.

The 840 series comes in a slim chassis with a very tidy PCB, and Samsung’s included Magician software is an excellent value add. The mounting kit and SATA-to-USB adapter are nice touches to the whole package, too. There are certainly SSDs available that offer better consistency in terms of performance, not to mention a healthier balance between read and write speeds, but the Samsung 840 Series SSD does offer solid value. At a price of $189.99 and and a formatted capacity of 232.88GB, this SSD costs about $0.82 per gigabyte. That’s not necessarily the absolute best value we’ve seen thus far, but it’s close.

Depending on your storage requirements, a 250GB Samsung 840 SSD could be the only drive you need, and if you’re looking to save some cash on a build or when upgrading a notebook, slapping in one of these babies could be a great way to do so. You’d get overall strong performance and obviate the need for a second storage drive, all for well under two hundred bucks.

Like its predecessor, the Samsung 830 Series, the 840 had high-performing read and lower-performing write speeds, which tells us that this is an area Samsung needs to work on. The Samsung MDX controller inside these drives has promise, but the third-party controllers other SSD OEMs are using might be a more robust alternative right now.

If you’re looking around the high end of the market for an SSD, keep moving.  However, the 250GB Samsung 840 is a pretty good drive that offers a great value for your dollar if you're interested in something a bit more cost-effective.