Last year Plextor released the M6e PCIe SSD, an M.2 form-factor SSD that supports data transfers over 2 PCIe lanes, not just SATA. We're on the cusp of breaking out of the SATA bottleneck that now constrains most SSDs. Unfortunately, very few motherboards in 2014 had M.2 ports, and while they're now becoming common, most still use SATA instead of PCIe. To keep the M6e from being bottlenecked, Plextor slapped the drive onto a circuit board and shipped a PCIe card version that is one very, very fast SSD for its price (about $1 per gigabyte). Now Plextor has released the M6e Black Edition, which is the exact same SSD, but with a classier covering and a heatsink bolted on.
The M6e Black Edition is Plextor's attempt to cater to gamers. They got complaints about the M6e's naked green board, they told me; the Black Edition definitely looks nicer, but it unfortunately comes with a higher price. It's currently selling in 128GB ($200), 256GB ($300), and 512GB ($530) variants on Newegg. To be fair, those are the MSRP prices for the stock M6e, but street price has brought the older card down to $160 for 128GB and $253 for 256GB. That's a substantially better price, if you don't care about the heatsink or aesthetics of the drive.
Whichever drive you get, here are the specs straight from Plextor:
| Capacity | Access Type | MB/s, 4KB Input/Output per second |
| 128GB | Sequential Read/Write | 770 MB/s read, 335 MB/s write |
| 128GB | Random Read/Write | 96,000 IOPS read, 83,000 IOPS write |
| 256 GB | Sequential Read/Write | 770 MB/s read, 580 MB/s write |
| 256 GB | Random Read/Write | 105,000 IOPS read, 100,000 IOPS write |
| 512GB | Sequential Read/Write | 770 MB/s read, 625 MB/s write |
| 512GB | Random Read/Write | 105,000 IOPS read, 100,000 IOPs write |
As is common with SSDs, the larger drives can hit substantially faster write speeds. We got a 128GB version of the M6e Black Edition in for testing, and faced it off against a few SSDs we had on hand, the newest of which are the SATA Samsung 850 series and Plextor's M6e placed in an M.2 slot. Unfortunately, because our motherboard only supports SATA over M.2, our other M6e drive isn't hitting full PCIe speeds.
Here are some basic performance results from Crystal Disk Mark.
| SSD | Sequential Read | Sequential Write | 4K Random Read (QD=32) | 4K Random Write (QD=32) |
| Plextor M6e Black PCIe (128GB) | 730 MB/s | 330 MB/s | 275 MB/s | 332 MB/s |
| Plextor M6e M.2 (256 GB) | 664 MB/s | 544 MB/s | 262 MB/s | 215 MB/s |
| Samsung 850 EVO (250 GB) | 510 MB/s | 493 MB/s | 390 MB/s | 334 MB/s |
| Samsung 850 Pro (1TB) | 540 MB/s | 501 MB/s | 400 MB/s | 349 MB/s |
| Samsung 840 EVO (1TB) | 512 MB/s | 494 MB/s | 351 MB/s | 351 MB/s |
As you can see, the smaller 128GB PCIe drive doesn't have the write throughput to beat the SATA SSDs, but it easily breaks past SATA's limitations for read speeds. The 256GB M6e in our M.2 slot hits the SATA speed cap, limiting its read speed to 664 MB/s, but is much more competitive in write speeds.
Most importantly, Plextor has updated the M6e's firmware to improve 4K performance, and you can see noticeable results between the Black Edition (firmware 1.05) and standard (still on 1.0) above. Alongside its firmware updates, Plextor has also updated its PlexTurbo software to version 2.0. PlexTurbo functions similarly to Samsung Magician, caching data to RAM to speed up performance. Like Magician, it looks great on benchmarks but often isn't noticeable in real-world usage. An update to the PlexTools software will allow PlexTurbo 2.0 to work on the vanilla M6e, as well.
Unfortunately we don't have enough PCIe SSDs on-hand to do an in-depth comparison of speed and storage consistency, but we'll be building up a library of data towards that goal. Reviews of the M6e Black Edition at PCPer, Tweaktown, Legitreviews and elsewhere have already done a good job of showcasing the drive's strengths. In short: it's fast, though it doesn't completely saturate a PCIe x2 connection, and firmware update aside, it's no faster than the M6e of 2014.
If SSD aesthetics are vitally important to you, the M6e Black Edition is easily the best choice around for a PCIe SSD—mainly because most of the competition is dramatically more expensive. If you don't care about looks, we'd recommend the standard M6e instead. It's about $50 cheaper, and the M.2 drive is more easily removable from the PCIe board, which is convenient if you ever want to plop it into a motherboard M.2 slot.
Final note: While the M6e Black Edition is essentially a prettier retread of an existing SSD, we're excited for Plextor's next drive releasing later this year: the M7e, a PCIe x4 model that will be able to hit read speeds of 1400 MB/s by using more lanes.
