Samsung 840 Series TLC 250GB SSD Review

Samsung leads the way by introducing the world's first SSD equipped with TLC NAND into the market. The Samsung 250GB 840 Series SSD looks to shake up the market by providing an excellent dollar-to-performance ratio by leveraging low cost NAND and the high-powered MDX controller. Does its performance equal the value expectation?

Samsung 840 Series TLC 250GB Basics

Samsung's release of the 840 Series takes the innovative approach of releasing the world's first TLC Triple Level Cell) NAND-equipped SSD. TLC brings with it many advantages, but a few notable disadvantages as well.

TLC stores three bits per cell, giving it higher density than MLC (two bits per cell) and SLC (one bit per cell), but also suffers lower write speeds and endurance as a direct result of the increased three bits per cell.

One of the primary reasons for the development and integration of TLC NAND into the market is the huge price decreases that it is expected to bring along with it. NAND is the most expensive component on SSDs, even though the price of NAND has been falling exponentially.

In 2010, customers were paying $3 a GB for capacity on SSDs, but today this has stabilized to $1 per GB on average, with sales and good deals netting prices of 80-90 cents per GB after mail in rebates and other incentives. There have even been several instances where customers have been able to pick up previous generation SSDs for under 60 cents per GB.

The price of NAND has been falling for several reasons; one of these being the process shrinks as the technology matures and simply requires less silicon. Each process shrink brings about an incremental drop in prices as the density increases.

Even with these decreases in cost, the average large capacity SSD still costs up to nine times more than a comparable capacity HDD. It will surely be some time before we will witness commoditization of SSDs, but assuredly, it will happen. The day will come when a user will walk into a big box store such as Fry's Electronics or Best Buy and every pre-built computer will be sporting a Solid State Drive.

This is the central motivation for the impending explosion of TLC NAND into the SSD market. Once TLC NAND is implemented in mass production the prices should drop tremendously for the value segment, while MLC will continue to dominate the performance-driven upper end.

As the larger OEMs transition to mass TLC production, with the NAND foundries chugging away, the price of NAND should fall further.

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TLC NAND brings with it lower write speed and lower endurance. This brings about the need to combat these eventualities with more refined firmwares, error correction, and enhanced NAND management techniques. Low write speeds for an SSD still enjoy a tremendous latency advantage over HDDs, and with low percentages of write activity in mixed read/write workloads the NAND can still produce enough speed to provide the large majority of users with more than enough speed.

The most concern comes from the reduced endurance of TLC. A few short years ago NAND management techniques simply were not sophisticated enough to squeeze enough endurance out of the product to create a viable solution. The typical expected life span of a consumer SSD is 5 years, and meeting that goal has always been the real hurdle that TLC needed to overcome to begin its widespread use.

Samsung pairs own TLC NAND with its powerful triple core MDX controller, which provides enough processing power to extract the desired performance characteristics from the NAND in both performance and endurance. After our review of the Samsung 840 Pro it is hard not to be impressed with the overall performance of the MDX controller. With the MDX controller and Samsung's firmware implementation producing enough horsepower to dominate the steady state testing in a large field of competitors, it will be interesting to test the performance of the new Samsung 840 Series featuring its TLC NAND and see if Samsung has delivered another winner.