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
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  • sonny73n - Wednesday, August 30, 2017 - link

    Got my 840 Evo when it first released and it was the last Samsung product I ever bought. I have no idea why many praise Samsung products. I had a Samsung plasma TV and two horizontal black lines appeared only after 14 months, 3 more appeared 2 months after. Then it became unwatchable. Now let's not talk about Samsung phones.
  • bug77 - Wednesday, August 30, 2017 - link

    I guess you have a thing for picking bad products? Plasma (with its known shortcomings) over LCD? 840EVO when planar TLC is just about as bad as it gets?
    No, you can't blame this on Samsung. Granted, their products, with few exceptions, are definitely average, but so is their pricing.
  • sonny73n - Wednesday, August 30, 2017 - link

    "No, you can't blame this on Samsung." Haha ok. Who are you to tell me not to voice my reasons? It was my money, not yours. Who would not expect a 3D Samsung plasma TV last for at least 3 years (2 hrs/day). And who would have thought a giant SSD brand like Samsung released something like the 840 Evo. Blame or not to blame, it's not important. I'd just never buy anything from a company that would up for sale half-baked products with/without knowing their shortcomings. Did they sell some phones that exploded recently? See, this is what I'm talking about.

    Until you get a Samsung blown up in face, everyone else's reasons for not buying Samsung are irrelevant.
  • chrnochime - Wednesday, August 30, 2017 - link

    Hi Samsung fanboy. You really going to say plasma is worse in every way over LCD? Ignoring the black level and response time? Okay then.
  • Alexvrb - Wednesday, August 30, 2017 - link

    Bug never said plasma was worse in every way. He did say it had known shortcomings, which it does - like longevity. Plasma also has some advantages, although it's dying off in favor of OLED on the high-end. With that being said, yes in this case Samsung DID sell him a lemon. Even with a plasma you should get a good few years of service, at least.
  • Alexvrb - Wednesday, August 30, 2017 - link

    Way to assume things, buddy. I'm not a Samsung fanboy, FAR from it. I don't currently own any other Samsung products outside of their SSDs. The fact is that the 850 Evo is the king of affordable SATA SSDs, period. Sorry for not being biased and preferring a superior product despite being Samsung. The 850 Pro is better in some heavy workloads but is a lot more expensive. Although for the record the 840 Evo was actually OK, I've got a system with the last firmware released and it has been fine. The 830 was also solid.

    I don't have much personal experience with their recent TVs, and I've only used their latest model phones for a few minutes here or there. Although I don't have any strong inclination to defend them as a company, I would bet your experience is rare. TVs are a crapshoot anyway. Their phones *generally* seem solid, even if I occasionally rail against them for lack of easily replaced batteries and SD card slots for some models - aside from the most obvious butt of many jokes, the last gen Note. Again, this is coming from someone who rarely buys Samsung.
  • tyaty1 - Thursday, August 31, 2017 - link

    Personally I am happy with their Series 6 TV from 2011, and I had no issue with their SSD-s.
    (Though I currently use a 256gb Crucial M550 in my notebook, which was 118 USD in 2015)
  • sonny73n - Monday, September 4, 2017 - link

    Alexvrb, are you and bug77 the same person? If not, why are you responding to chrnochime's reply meant for bug77?

    It's the first I've heard (from you) that TLC is better than MLC. An TLC drive might have performance than an MLC if it has better controller. But for endurance, generally MLC is better than TLC and this is the fact. When you made a statement like "MLC or not, the TLC Evo is better...", people can only assume one thing about you. Anyway, you should have a little read about SSD tech before making such assertion.
  • chrnochime - Wednesday, August 30, 2017 - link

    There are people who care a lot more about RATED endurance than performance. You obviously aren't one of them, and your opinion about the EVO being best option != the truth/fact. LOL
  • Alexvrb - Wednesday, August 30, 2017 - link

    They're also high endurance. 850 Evos have excellent endurance, and in real endurance torture testing they even exceed expectations. But feel free to spread FUD like a boss.

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