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Plextor M6S series review: Slow performance for the price

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The Good The Plextor M6S has low power consumption and is a great performance upgrade for a computer that still runs on a regular hard drive.

The Bad Compared with other solid-state drives on the market, the M6S' performance is disappointing. It also comes with only a short three-year warranty.

The Bottom Line With unimpressive performance that doesn't match its high price, there's no reason why you should pick the Plextor M6S over other SSDs on the market.

6.8 Overall
  • Setup 8
  • Features 7
  • Performance 6
  • Support 7

When compared with any consumer-grade hard drive, the Plextor M6S solid-state drive (SSD) is energy-efficient, not to mention much faster. When you stack it up against other SSDs, however, its slower performance just doesn't measure up.

Available in three capacities -- 128GB, 258GB, and 512GB, with the suggested retail prices of $140, $250, and $500, respectively -- the new M6S is the first I've seen from Plextor that costs less than $1 per gigabyte at launch. That's a welcome change from the company, but they're still much more expensive than competing devices.

If the Plextor sold the M6S's three versions at around $70, $150, and $300, then I'd recommend them. But at their current prices, they don't deliver performance you should expect. That makes them far from the best choices on the market. Until their price goes down significantly, choose something from this list, instead.

The new M6S share the same design as previous SSDs in Plextor's M5 series. Dong Ngo/CNET

Design and features

The new M6S series shares the same dimensions as previous SSDs from Plextor, the M5 series . It's a standard 2.5-inch internal drive that use the now-common 7mm thickness. This means the drive can be used in all desktops, as well as standard laptops and certain ultrabooks.


128GB 256GB 512GB
Interface SATA 6Gbps SATA 6Gbps SATA 6Gbps
Controller Marvell 88SS9188 Marvell 88SS9188 Marvell 88SS9188
NAND Flash memory 19nm Toshiba toggle mode 19nm Toshiba toggle mode 19nm Toshiba toggle mode
Random write 75,000 IOPS 80,000 IOPS 80,000 IOPS
Random read 88,000 IOPS 90,000 IOPS 94,000 IOPS
Sequential write 300 MB/s 420 MB/s 440 MB/s
Sequential read 520 MB/s 520 MB/s 520 MB/s
Mean time between failures 1.5 million hours 1.5 million hours 1.5 million hours
Energy consumption .25W .25W .25W
MSRP $139.99 $250 $500
Warranty 3 years 3 years 3 years

On the inside, the M6S is actually a step down from the previous M5 Pro. The new drive uses Marvell's 88SS9188 controller, which has only four channels, compared to the eight-channel controller used in the previous generation. This generally means lower cost and less power consumption, but also slower performance.

That said, with the release of the M6S, it's the first time Plextor has dipped its toes into the budget market of solid-state drives. With the M5 Pro and M5 Pro Xtreme, the company intended to aim for the top end of the market in terms of both performance and cost.

The M6S comes with a modest mean time between failures (MTBF) of 1.5 millions hours (this is compared with 2 millions hours for others) and a relatively short warranty of three years (as opposed to the five-year plans that come with many high-end drives.) MTBF basically means the average elapsed time before the drive might fail. There's no support for hardware encryption, either, which is not a big deal for home users, but for business users, it means they can't keep their data safe in case of theft.

The M6S comes with very high endurance, which is measured in program/erase (P/E) cycles. You can write some 65GB of data to it each and every day for three years before it's likely to become unreliable. Most of us don't write that much per day at all, and definitely not every day. (Read more about endurance here.) That said, it's safe to say that you'll find other reasons to replace the drive before it runs out of P/E cycles.

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