Final Words

The Crucial BX200 comes in last place as often as not. The Crucial BX300 doesn't entirely reverse that, but it still provides one of the biggest generational jumps the SSD market has seen. Micron has learned from their mistakes with the BX200 and produced a worthy successor to the BX100. With the MX300 doing so well as a mainstream SSD with entry-level pricing, the focus of the BX line has shifted from simply being the cheaper option to being the drive designed specifically for the smaller capacities demanded by cost-conscious consumers.

Micron's large 384Gb 3D TLC die is ill-suited to making small SSDs, as 120-128GB SSDs end up only having 3 NAND chips on a four-channel controller, and even at larger capacities the flash is not well balanced across the controller channels. For the next generation of 3D NAND, Micron is addressing this issue by manufacturing both a large 512Gb die and a smaller 256Gb die. Since that 64-layer 3D NAND is still ramping up to full production, Micron has chosen for the BX300 to use their 256Gb 3D MLC that allows for a small SSD to be reasonably fast and free of the downsides of the TLC NAND that dominates the entry-level SSD market.

It's a bit of a puzzle how Micron can afford to sell an MLC SSD for less than their TLC SSD without making serious compromises elsewhere like using a DRAMless controller. But as long as they're willing to sell the BX300 at these prices, it's a great product.

The BX300 only has a few notable weaknesses. Micron's 32L 3D NAND is unusually power-hungry during sequential reads, despite being otherwise quite efficient. This also affects random reads to some extent. The BX300's peak performance is on average slightly below top-tier SATA drives like Samsung's 850 PRO and EVO and the Intel 545s, and it is outperformed by other 3D TLC drives like the MX300 and ADATA SU800 when they're able to make good use of their SLC caches. But this is offset by how well the BX300 retains its performance under heavier workloads and when operating with a nearly-full drive. In that respect, it has a significant advantage over the Crucial MX300.

  120-128GB 240-275GB 480-525GB 960-1050GB 2TB
Crucial BX300 $59.99 (50¢/GB) $89.99 (38¢/GB) $149.99 (31¢/GB)    
Crucial MX300   $99.99 (40¢/GB) $159.99 (32¢/GB) $289.99 (29¢/GB) $549.00 (27¢/GB)
ADATA SU800 $56.68 (44¢/GB) $91.99 (36¢/GB) $168.58 (33¢/GB) $265.00 (26¢/GB)  
ADATA SU900   $108.99 (43¢/GB) $197.80 (39¢/GB)    
ADATA XPG SX950   $109.99 (46¢/GB) $214.99 (45¢/GB)    
Intel SSD 545s   $99.99 (39¢/GB) $169.99 (33¢/GB)    
Samsung 850 PRO   $114.99 (45¢/GB) $212.19 (41¢/GB) $420.99 (41¢/GB) $897.99 (44¢/GB)
Samsung 850 EVO   $89.99 (36¢/GB) $174.75 (35¢/GB) $299.99 (30¢/GB) $715.00 (36¢/GB)

The Samsung 850 EVO is available with very competitive pricing at the moment, shutting many drives using Micron 32L 3D NAND out of the market. The MSRP of the 480GB BX300 we tested is low enough to beat basically everything on a price per GB basis, and is far enough below the Samsung 850 EVO that it isn't an automatic decision to get the Samsung instead. The 240GB BX300 will debut with the same price as the 250GB Samsung 850 EVO, making the Samsung the better option for now.

The smallest capacity of the Crucial BX300 may prove to be the most popular and most competitive. There are other 120GB drives on the market that are priced a bit lower, but the BX300 has the advantage that it uses 3D MLC NAND, doesn't use a DRAMless controller and uses all four NAND channels on its controller. The 120GB BX300 will be slower than the 480GB model we tested, but it will retain the general characteristic of performing almost as well when it is full as when empty. This is far more important at such small capacities. The 120GB BX300 also benefits from lack of competition from Samsung: the planar TLC-based 750 EVO is not available at competitive prices and the 120GB 850 EVO and 128GB 850 PRO were discontinued when Samsung moved from 32L 3D NAND to 48L 3D NAND.

Power Management
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  • lilmoe - Tuesday, August 29, 2017 - link

    Question. This is provably unlikely, but is binning layers possible?
  • lilmoe - Tuesday, August 29, 2017 - link

    Probably*
  • Billy Tallis - Wednesday, September 6, 2017 - link

    3D NAND is not really built one layer at a time. The first stage of building the memory array is to make a tall stack of alternating materials, and then vertical strings of memory cells are formed through that stack by etching deep but narrow holes and filling them with the remaining components. That high aspect ratio etching step is one of the main limiting factors in scaling layer count. If you push the layer count too far, you end up with memory cells in layers near the top of the stack having significantly different properties from the ones near the bottom of the stack.

    It's relatively unlikely to have an individual layer somewhere in the middle of the stack be dead/defective across that entire layer. It's more common to see an entire vertical column fail, which involves a much smaller number of memory cells.
  • Radio-Zone - Wednesday, August 30, 2017 - link

    Thanks for the information!!!
  • Ej24 - Wednesday, August 30, 2017 - link

    Congratulations Micron you're almost back to where you were 2 years ago in performance with the m550, Mx100 and mx200. I've always been a huge fan of crucial SSD's. Great bang for the buck for MLC drives. But the last year or so it's been hard to keep praising crucial.
  • m16 - Sunday, September 3, 2017 - link

    It's an interesting move, but all in all, due to the shortage, any SATA drive will do for anyone that is looking for a switch to SSD on the desktop, while power might be the top issue for laptops.

    There's the RAM caching on some of their drives which is very good all in all, especially for computers that have AMD CPUs, that can't use Intel's caching technology to speed things up.
  • keta - Wednesday, September 6, 2017 - link

    Over two-and-a-half years ago (January 2015), I bought a 256GB MX100 for $95. That worked out to $0.371/GB, or a little less than what the BX300 is going for today ($0.375).

    I would be willing to pay the same rate if it meant better performance, but using the ATSB Heavy stats in Bench, it seems that my old MX100 outperforms the BX300 in both data rate and latency. Are the 2015 ATSB Heavy stats comparable to the 2017 stats? Is it really the case that SATA SSD price/performance is worse than it was 2.5 years ago?
  • Billy Tallis - Wednesday, September 6, 2017 - link

    The average data rate and latency stats for the ATSB tests should be comparable between the 2015 and 2017 test suites. The workload didn't change, but the OS version and motherboard did. Next month or maybe late this month, I'll pull the MX100 from my gaming machine and put it through the 2017 test suite.
  • keta - Wednesday, September 6, 2017 - link

    Thanks! I'd be super interested in a 'long-view' piece that puts some of the older flagship SSDs (X-25M, Vertex 2, MX100) through the present-day latency/consistency analysis that AT has developed. And maybe throw in that old WD Scorpio as well, not just to see how far we've come from spinning drives, but also to put the differences between SSDs in perspective!
  • Lolimaster - Thursday, August 9, 2018 - link

    And now in Peru you can find the BX300 120GB for $35 xD.

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