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Samsung 840 Pro Series 256GB review


  • Excellent performance
  • Nicely priced
  • Five year warranty


  • Slower Toggle Mode 1.0 memory interface

Samsung is the largest flash manufacturer in the world, but most of its sales volume goes to companies like Apple, which then use the memory in their own products. Consumer products have become increasingly important to the Korean manufacturer, however, and its mass market SSDs have attracted quite a bit of attention. Late last year, Samsung launched a pair of SSDs aimed at enthusiasts and the mass market – the Samsung 840 (which we've previously reviewed) and 840 Pro Series 256GB we're reviewing here.

Both use Samsung's MDX memory controller. The new chip contains three ARM Cortex-R4 cores as opposed to the 830 family's ARM9 chips, and the cores run at a higher clock speed (300MHz as opposed to 220MHz). The difference between the Samsung 840 and the 840 Pro is that the 840 Pro uses Samsung's Toggle Mode MLC Flash rather than the newer, cheaper, and slower TLC (triple-level cell) NAND in the Samsung 840.

The warranty terms are also different – the Samsung 840 has a three year warranty, while the 840 Pro has one for five years. Interestingly, the TLC-equipped Samsung 840 uses Toggle Mode 2.0 NAND while the 840 Pro uses Toggle Mode 1.0 memory. Toggle Mode 2.0 NAND should theoretically be faster than the 1.0 flavour, but Samsung opted to use the slower 1.0 interface with its higher performing 840 Pro drive.


Our review unit was tested using an Asus P877V Deluxe motherboard with 8GB of DDR3-1600 RAM and an Intel Core i7-3770K CPU. The P877-V Deluxe offers multiple SATA controllers from Intel and Marvell; the V300 was connected to Intel's 6G SATA port.

The performance figures for AS-SSD and SiSoft Sandra reflect a drive's performance in a particular type of data workload. Sequential read/write tests measure an SSD's capabilities when reading or writing a large block of contiguous data. A single large movie or ISO image will test a drive's sequential performance (assuming that the target drive isn't badly fragmented).

In AS-SSD, the Samsung 840 Pro hit sequential read/write speeds of 518 and 481MBps respectively. That's neck-and-neck with the OCZ Vector 256GB (which hit 509.42 and 495.72 MBps respectively). The standard Samsung 840 was just as fast on reads (517MBps), but markedly slower in writes (244.75MBps).

The 4K read/write tests ascertain the performance of an SSD or HDD when reading and writing small chunks of data. These small read/writes are vital to the everyday performance of a storage solution. The "64 Threads" test in AS-SSD means that the benchmark program spins off 64 separate 4K read/write tasks. This stretches the controller's ability to manage such workloads, but also provides a more realistic performance metric – an operating system is constantly reading and writing data to multiple services and programs simultaneously.

AS-SSD's 64-thread 4K benchmark test showed the Samsung 840 Pro is slightly faster than the OCZ Vector (381MBps read and 299MBps write against 358MBps read and 304 MBps write). Again, the cheaper Samsung 840 is closer on read performance (329MBps) than on writes (187MBps).

The random read/write performance data from SiSoft Sandra that we also quote is a measure of a drive's sustained performance when reading and writing a contiguous block of information to a randomly chosen location. These metrics are important because they collectively measure the different types of storage tasks an SSD or HDD performs, even if they don't represent user workloads.

In SiSoft Sandra's random read/write tests, all three drives broke 500MBps – likely the effective maximum for a SATA 6G drive. Read/write scores for the OCZ Vector and 840 Pro were nearly identical, at 530MBps reads and 510 MBps writes. The Samsung 840 hit 530MBps read, but just 246MBps write.

Finally, there's PCMark 7, which is a different type of test. The benchmark uses real storage workloads created by recording traces of hard drive activity when playing games, loading music or video, or copying files. These traces are used to measure the performance of storage products in comprehensive real-world scenarios.

The difference between SSDs in PCMark 7 tends to be much smaller than what we see in other synthetic tests. Here, the Samsung 840 Pro nudged out the OCZ Vector, at 5,588 compared with 5419. That's a new single drive record here – the 840 Pro beat the OCZ Vector by 3.1 per cent and the Samsung 840's 5,265 by 6.1 per cent.


The Samsung 840 Pro 256GB can be picked up for £180, and it’s a great high performance SSD for the money. The OCZ Vector 256GB is very similar in terms of performance, and also carries an identical five year warranty – but it’s a bit more expensive at around £210.

Overall, the Samsung 840/840 Pro are a well-targeted set of drives. At the high end, the 840 Pro is competitively priced, and it grabs one of our Best Buy awards. It is, for the moment, the high-end SSD to beat.