Samsung's 840 EVO SSD family: Fast, large, and in charge

If you're a laptop user who's skipped the SSD experience because of the breed's lack of capacity, your drive has arrived—or it will in the first week of August. Samsung's new 840 EVO family of drives will be available in capacities up to a whopping 1TB. And these drives are aggressively priced: $110 for 120GB version, $190 for the 250GB, $370 for the 500GB, $530 for the 750GB, and a mere $650 for the 1TB. Mere is a relative concept, of course, but 65 cents per GB is a new low for retail SSDs.

The larger part of the secret behind the 840 EVO's increased capacity is 3-bit MLC (Mulit-Level Cell) NAND which by it's very nature (it stores 3 bits of information) offers a third more capacity than the 2-bit MLC NAND used in most current generation drives. Also helping fit more stuff into less space is the 19nm manufacturing process used to produce the NAND. Samsung for some reason is calling this 10nm-class, or 1x NAND, but they assured us that it's 19nm.

Samsung also promises that the 840 EVO will outperform most of the current SSD crop, but the Samsung 840 Pro will remain the company's flagship solid-state drive. To that end, Samsung is treating part of the NAND as 1-bit SLC (Single-Level Cell), which gives it that technology's superior speed and endurance. It's then employed as cache for the rest of the NAND. The technology is called TurboWrite and it's part of the repertoire of the new MEX (up from the 840's MDX) controller used on the EVO.

Samsung is also providing a operating system-level driver called Rapid that leverages what Samsung calls today's PC's over-provisioning of memory. In other words, it steals some of your system's RAM and uses it as cache. Beyond that, it uses smarts to adapt to usage patterns over time, rendering the cache more effective.

PCWorld is putting a 250GB version of the 840 EVO through its paces as this is being written, so check back on Friday for a full review, including a side-by-side hands-on comparison with the 840 Pro. Even if performance isn't best-of-breed, the capacity and low price per gigabye of the 840 EVO should have a significant impact on the market in short order.

Editor's note, 7/25/2013: This story was updated to indicate that Samsung's 840 Pro will remain Samsung's highest-performance SSD.

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