Micron has finally introduced a second consumer SSD with 3D NAND flash. Rather than a high-performance NVMe drive, they've brought back the entry-level BX product line for the Crucial BX300.

At Computex 2014, Micron introduced the Crucial MX100, the first SSD to use their 16nm MLC NAND. The MX100 was a hit with great performance and great pricing. It was followed up in 2015 by the Crucial MX200, which wasn't much of an improvement over the MX100. But at the same time, Crucial introduced a second product line with the BX100. Using the same 16nm MLC but a cheaper Silicon Motion controller, the Crucial BX100 continued to offer good performance for most purposes and was also the most power efficient SSD of its time.

Later in 2015, the consumer SSD market began to rapidly switch over to TLC NAND: consumers wanted cheaper SSDs, but only Samsung had usable 3D NAND, so planar TLC was the way to increase capacity. Micron introduced the Crucial BX200 in November 2015 as their first SSD to use TLC NAND. The BX200 successfully reduced price per GB, but sacrificed a great deal of performance and power efficiency in the process. The BX200's fate was sealed by drives like the ADATA SP550 that used faster and cheaper SK Hynix TLC to undercut the BX200's pricing while offering somewhat better performance.

Finally, in June 2016 Micron's 3D NAND was ready for mass market use, and the consumer SSD market's race to the bottom was put on hold. Micron introduced the Crucial MX300 using a high-performance Marvell controller like previous MX series SSDs, but using the TLC variant of their 3D NAND rather than MLC. The MX300 thus was serving as successor to both the MX200 and BX200, and it has done the job well with good performance and far better power efficiency than any previous TLC SSD (even considering Samsung's 3D TLC-based 850 EVO).

Crucial MX Series Specifications
Model MX100 MX200 MX300
Controller Marvell 88SS9189 Marvell 88SS1074
NAND Micron 16nm
128Gbit MLC
Micron 384Gbit
32-layer 3D TLC
Capacities 128GB-512GB 250GB-1TB 275GB-2TB
SLC Caching No Some Models Yes
Encryption TCG Opal 2.0 & IEEE-1667 (eDrive)
Warranty Three years
Write Endurance 72 TB 80-320 TB 80-400 TB
Launch Date June 2014 January 2015 June 2016

The main limitation of the Crucial MX300 stems from the odd capacity of Micron's 32-layer 3D TLC parts. The 32L TLC die is Micron's 32L 256Gb MLC operated as a TLC chip, yielding a capacity of 384Gb (48GB) per die. It is awkward to build SSDs with standard power of two capacities out of such chips, so Micron initially introduced the MX300 with a 750GB (768GB raw) capacity model. The rest of the MX300 lineup used capacities that were slightly above the standard sizes (eg. 525GB instead of 512GB), which still left the MX300 with more overprovisioning than a typical consumer SSD. The odd capacity effect is most pronounced with the smallest MX300, the 275GB model. Micron didn't go any smaller than that because a drive in the ballpark of 128GB would use only three TLC dies, wasting one of the four channels on most SATA SSD controllers.

Micron's upcoming second generation 3D NAND parts are designed with TLC in mind as the primary use, and Micron will be producing both 256Gb and 512Gb parts. But this new 64-layer 3D NAND is still ramping up in production. Intel has shipped limited quantities in their 545s, but most of the early 64L NAND is going to the enterprise SSD market.

That's where the new Crucial BX300 comes in. The BX300 brings MLC NAND back to the Crucial product line for the sake of making smaller capacity entry-level SSDs. The Crucial BX300 will be produced in capacities from 120GB to 480GB using Micron's 256Gb 32L 3D MLC. Micron is again using a Silicon Motion controller for the BX line, this time the SM2258. Micron has not opted to use the DRAMless SM2258XT variant and instead has equipped the BX200 with 256MB to 512MB of their own DDR3.

Crucial BX Series Specifications
Model BX100 BX200 BX300
Controller Silicon Motion SM2246EN Silicon Motion SM2256 Silicon Motion SM2258
NAND Micron 16nm
128Gbit MLC
Micron 16nm 128Gbit TLC Micron 256Gbit
32-layer 3D MLC
Capacities 120GB-1TB 240GB-960GB 120GB-480GB
SLC Caching No Yes Yes
Encryption None
Warranty Three years
Write Endurance 72 TB 72 TB 55-160 TB
Launch Date January 2015 November 2015 August 2017

On paper, the BX300 does not appear to be making any significant compromises to reach low price points. In some respects it is superior to the MX300, and it certainly seems like it will have lower profit margins for Micron. The BX300 may be the kind of product that only a vertically-integrated manufacturer like Micron can successfully bring to market in the midst of an industry-wide NAND shortage. ADATA uses the same controller and NAND in their SU900 and SX950 SSDs, but those are selling for significantly higher prices than the Crucial MX300, not lower. The BX300 may turn out to be a short-lived stopgap product to go after a segment of the market that the MX300 is ill-suited for. A replacement for both the MX300 and BX300 using 64L TLC will probably show up as soon as Micron can spare the NAND. Certainly by Computex in June 2018 we should expect a new product, but I wouldn't be surprised to hear about something at CES in January.

Crucial BX300 Specifications
Capacity 120GB 240GB 480GB
Form Factors 2.5" 7mm
Controller Silicon Motion SM2258
NAND Micron 256Gbit 32-layer 3D MLC
DRAM (DDR3) 256MB 256MB 512MB
SLC Write Cache 4GB 8GB 16GB
Sequential Read 555 MB/s 555 MB/s 555 MB/s
Sequential Write 510 MB/s 510 MB/s 510 MB/s
4KB Random Read  45k IOPS 84k IOPS 95k IOPS
4KB Random Write  90k IOPS 90k IOPS 90k IOPS
Encryption No
Write Endurance 55 TB 80 TB 160 TB
Warranty Three years
MSRP $59.99 $89.99 $149.99

The Crucial BX300 is Micron's first MLC-based consumer SSD since the Crucial MX200. With the MX200, Micron experimented with using SLC caching on smaller capacities and had mixed success—peak performance was boosted a bit, but at the cost of creating more background work for the controller that hurt sustained workloads. For the Crucial BX300, Micron is using relatively small fixed-size SLC caches. Sequential performance and random write performance are rated the same across all three capacities, while random read performance is reduced a bit for the 240GB and is cut in half for the 120GB model. The rated write endurance numbers are probably chosen simply to be lower than the ostensibly higher-end MX300 model, rather than being based on actually lower expectations for drive lifetime. The MX300 does have lots of overprovisioning with which to reduce write amplification, but the BX300 has a reasonable amount too and the advantage of inherently higher endurance from using MLC instead of TLC.

Gallery: Crucial BX300

For this review, the our 480GB Crucial BX300 will primarily be compared against:

AnandTech 2017 SSD Testbed
CPU Intel Xeon E3 1240 v5
Motherboard ASRock Fatal1ty E3V5 Performance Gaming/OC
Chipset Intel C232
Memory 4x 8GB G.SKILL Ripjaws DDR4-2400 CL15
Graphics AMD Radeon HD 5450, 1920x1200@60Hz
Software Windows 10 x64, version 1703
Linux kernel version 4.12, fio version 2.21
AnandTech Storage Bench - The Destroyer


View All Comments

  • khon - Tuesday, August 29, 2017 - link

    I don't get the point of this product. If you care enough of performance to get MLC NAND rather than TLC NAND, why would you get a SATA SSD ? Reply
  • bill.rookard - Tuesday, August 29, 2017 - link

    Sometimes it's just form factor. You may have a laptop that only has regular SATA SSD's or are upgrading to a SSD from a spinny-disk (which are decidedly awful in laptops). Or - perhaps you have a NAS or server which uses 2.5" SATA drives, or a desktop that doesn't have an M.2 slot.

    There are lots of reasons to have a SATA option.
  • nathanddrews - Tuesday, August 29, 2017 - link

    True. I have a couple pre-NVME computers that need an upgrade, so that's why I go SATA. Reply
  • eek2121 - Tuesday, August 29, 2017 - link

    1) Buy M.2 adapter card.
    2) Use clover to boot from NVME
    3) ???
    4) PROFIT!!!
  • Alexvrb - Wednesday, August 30, 2017 - link

    The cheapest and easiest way to upgrade a conventional SATA-equipped system to an SSD is with a SATA SSD. Also M.2 is a form factor, not an interface. A lot of the entry-level / affordable M.2 drives are SATA-based. The added costs and complexities to get something substantially faster than SATA might not be worth it. Meanwhile a sub-$100 Evo drive can help revive an older system for cheap, it's the same price as competing products and it's somewhat better.

    Also, if you're talking about using Clover/Tianocore with a legacy non-UEFI bios, it's kind of a mild nuisance. Especially if you're doing it for someone else on a budget. Plus you still need to use the existing mechanical clunker SATA drive (well you could add a USB stick I guess) for the BIOS to boot and load Tianocore.

    Last but not least if you're talking about an older laptop, you might very well be stuck with SATA or mSATA. So might as well make the most of it. There are a lot of OEM systems with decent enough processors, saddled with horribly slow HDDs. Easy and cheap way to rev them up.
  • leexgx - Saturday, September 2, 2017 - link

    he thinks the laptop is a PC :P Reply
  • MajGenRelativity - Tuesday, August 29, 2017 - link

    People also have concerns about life expectancy of their hard drives. As far as performance, SATA is still cheaper than PCIe, so cost plays a factor as well. Reply
  • BrokenCrayons - Tuesday, August 29, 2017 - link

    Although I'll probably NEVER hit an endrance wall with TLC NAND, since the prices for TLC and MLC in are disturbingly close at this point, I see no reason not to purchase MLC. In fact, I just bought two 240GB and one 480GB SATA SSD two weeks ago and all of them were 3D MLC because there was no difference in price. I think it might be more reasonable to ask why anyone would bother with TLC in SATA or any other form factor given the current state of the market. Reply
  • littlebitstrouds - Tuesday, August 29, 2017 - link

    Really it's quite easy... If MLC is better for endurance, and we can't find SLC anymore, without going full enterprise, anyone who engineers systems for stability will inevitably take a MLC nand storage device over a TLC, all other parts being equal. Just because you can't see a reason, doesn't mean there isn't a market for it. I guarantee you don't understand every aspect of every engineering problem that exists, which means you may not understand why a company, with shareholders, would devise such a product. Reply
  • sonny73n - Wednesday, August 30, 2017 - link

    Seriously, you said it's easy to see the reason why but you kept ranting on without giving us a reason why they keep producing TLC and selling them at the same price with MLC. Reply

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