SSD manufacturers are under constant pressure to reduce prices and increase capacity, but the pace of Moore's Law is never enough to satisfy consumers. As the SSD industry has matured, manufacturers have turned to other strategies for driving down costs, making tradeoffs to better suit what customers want. Early on, we saw a shift from single bit-per-cell SLC NAND to two bit-per-cell MLC, doubling capacity for the same size of chip (and therefore, cutting cost per GB in half). Currently, the industry is transitioning to 3D NAND techniques that allow for more storage capacity on a chip of a given size without requiring circuit elements and memory cells to shrink. Portions of the market are also shifting to use three bit-per-cell TLC NAND to get another capacity boost.

None of these advancements in storage density come for free. 3D NAND requires major changes to the manufacturing process, which is why only one of the four NAND manufacturers is currently shipping products with 3D NAND. Likewise, cramming more bits into the same memory cell has reprecussions. The more closely spaced voltage levels in the flash cells requires more careful control and more complicated error correction. It makes reading and especially writing slower, drives up power consumption and decreases durability. Everyone in the industry has struggled to create TLC-based SSDs that can compete on anything other than cost. Samsung has made the most use of TLC, aided by their lead in 3D NAND, but their TLC drives have had issues that have proven tough to stamp out. Despite the difficulty, most manufacturers now feel that TLC has a place in the market and that the downsides can be mitigated enough to suit consumers.

This brings us to Crucial's latest drive, the BX200. As the successor to the very successful BX100, it is a value-oriented 2.5" SATA drive. The BX200 moves to the newer Silicon Motion SM2256 controller and is Crucial and Micron's first TLC drive, using Micron's 128Gb 16nm TLC NAND. Micron's 16nm TLC was announced in June as intended for consumer applications. With a shift to 3D NAND planned for 2016, their 16nm TLC is something of a stopgap solution to further cut costs while temporarily stuck at the end of the road for planar NAND.

Silicon Motion's SM2246EN controller has been a popular choice for low-cost client drives, and when paired with MLC NAND it offers decent performance and very low power consumption. While it technically supports TLC NAND, only the successor SM2256 controller supports the more advanced LDPC error correction that is widely viewed as necessary to get sufficient reliability from a TLC drive. There are now several TLC drives on the market using the SM2256, competing primarily against each other and earlier SM2246EN drives with MLC, and MLC and TLC drives using Phison S10 controllers. Further up the price and performance scale are mid-range MLC drives and Samsung's TLC-based 850 Evo.

Crucial  480/500/512GB SSD Comparison
Drive BX100 BX200 MX200
Controller Silicon Motion SM2246EN Silicon Motion SM2256 Marvell 88SS9189
NAND Micron 16nm 128Gbit MLC Micron 16nm 128Gbit TLC NAND Micron 16nm 128Gbit MLC
Sequential Read 535 MB/s 540 MB/s 555 MB/s
Sequential Write 450 MB/s 490 MB/s 500 MB/s
4kB Random Read 90k IOPS 66k IOPS 100k IOPS
4kB Random Write 70k IOPS 78k IOPS 87k IOPS
Endurance 72 TB 72 TB 160 TB
Warranty 3 years

The BX200 specifications show only moderate performance increases over the BX100, except for the random read speed which is significantly decreased. The higher program and erase times of TLC NAND are probably the most difficult downside to mitigate, as SSDs have always been trying to compensate for their much higher latency than DRAM. Throughput can be increased by using multiple flash chips in parallel, but random read performance ultimately is limited by how long it takes the drive to fetch any data from the flash chips, so some decrease was probably unavoidable.

With the BX200 Crucial is retiring the 128GB capacity class. As flash memory gets cheaper, the fixed costs of the controller and other components come to dominate the budget and smaller capacity drives end up costing more per GB than mid-range capacities. Additionally, the smallest capacities have the least ability to provide parallelism, which can hobble their performance.

For most of the charts in this review, I've highlighted in blue the other TLC drives we've tested.

AnandTech 2015 SSD Test System
CPU Intel Core i7-4770K running at 3.5GHz (Turbo & EIST enabled, C-states disabled)
Motherboard ASUS Z97 Deluxe (BIOS 2501)
Chipset Intel Z97
Chipset Drivers Intel 10.0.24+ Intel RST
Memory Corsair Vengeance DDR3-1866 2x8GB (9-10-9-27 2T)
Graphics Intel HD Graphics 4600
Graphics Drivers
Desktop Resolution 1920 x 1200
OS Windows 8.1 x64
Performance Consistency
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  • paulgj - Monday, November 9, 2015 - link

    I just ordered a couple more BX100's 250GB
  • doggface - Tuesday, November 3, 2015 - link

    The MX100 was just brilliant, an easy recommendation.The BX100 has been my go to value SSD, that l I recommended to many friends. The bx200 is garbage which costs more? And is about as bad as a HDD. What the hell crucial. What the hell.
  • Luke212 - Tuesday, November 3, 2015 - link

    BX100 and MX100 were great.... how can they go backward so badly?
  • JDG1980 - Tuesday, November 3, 2015 - link

    It's looking more and more as though TLC is a big flop. It doesn't seem to provide substantial price savings, and it comes at a considerable cost in performance, durability, and reliability.

    For a TLC drive to be worth it, it would need to be 1/2 to 1/4 the cost per gigabyte of a MLC solution on the largest drives. It then might be acceptable for people who want moderately priced bulk storage that's cheaper than standard SSDs. But that's not close to being the case now, and it may never be.
  • CiccioB - Wednesday, November 4, 2015 - link

    Yeah, I still wonder if TLC is really reliable as producers advertise them.
    Samsung needed a "hack" to their 840 TLC series to solve data retention problems reducing life time.
    We do not know if others have done the same without (obviously) telling publicly. And if 850 series has it under the hood.
    I would go to MLC drives for few $ more. I feel them as more reliable and durable. And "feeling" is an important thing for me, as I put my data on them and saving few bucks may not really be an advantage when a TLC drive lives less then a MLC one.
    For performance, I bet anyone to be able to discern differences in real life form an SSD to another. This are "synthetic" tests, where source of data is faster than SSD speed (RAM). For whatever real usage, anything comes from sources that are slower (HDD, network, optical disks). Load times into RAM is limited, as you don't usually load GB and GB into it but during a benchmark.
    What it really matters is reliability, durability and price. TLC fails to make me comfortable with the first two criteria. Which, for me, are the most important ones.
  • CiccioB - Wednesday, November 4, 2015 - link

    "This are "synthetic" tests"
    These are synthetic tests.

    Edit button, please!
  • extide - Thursday, November 5, 2015 - link

    Yeah it seems like you really need to go to 3D NAND to get decent TLC -- the 850 EVO's have so far been pretty much great. That significantly larger feature size really helps the TLC out.
  • Beaver M. - Wednesday, November 4, 2015 - link

    No wonder I have been skipping reviews of new SATA SSDs for a few years now. Nothing can touch the Samsung ones, and thats sad.
  • ghanz - Wednesday, November 4, 2015 - link

    Review request: Please do a review of Sandisk Plus, their current lowest tier SSDs available in 120gb and 240gb capacities.
    Will be interesting to see how those compares to the BX100 and BX200 in similar capacities.
  • Mugur - Wednesday, November 4, 2015 - link

    I must buy another BX100 until the stocks will dry...

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