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 13.2.4.1000
Memory Corsair Vengeance DDR3-1866 2x8GB (9-10-9-27 2T)
Graphics Intel HD Graphics 4600
Graphics Drivers 15.33.8.64.3345
Desktop Resolution 1920 x 1200
OS Windows 8.1 x64
Performance Consistency
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  • Mugur - Wednesday, November 4, 2015 - link

    I must buy another BX100 until the stocks will dry... Reply
  • redzo - Wednesday, November 4, 2015 - link

    It's a disaster. I think that Crucial was better of not releasing the damn thing. What were they thinking? The performance gap is huge compared to samsung's evo. This product just shows that samsung rules TLC. All educated buyers will think twice before purchasing it even at 15/20$ lower than this. Reply
  • KAlmquist - Wednesday, November 4, 2015 - link

    What makes it a disaster is that Crucial is replacing a successful product (the BX100) with this thing. Keep the BX100 around, give the new drive a designation like AX100, market it as a budget alternative to the BX100, and the drive might be a modest success.

    When the BX100 disappears, that will leave the Samsung 850 EVO as the paradigm of the SATA SSD sweet spot, with good balance of performance, quality, and attractive pricing.
    Reply
  • paulgj - Monday, November 9, 2015 - link

    They should name it the BX50 :-) Reply
  • tabascosauz - Wednesday, November 4, 2015 - link

    The BX200 should be compared to the SP550 from ADATA. Both are budget drives, both SM2256 (which has left a much crappier first impression than the actually promising SM2246EN), both TLC, yet the SP550 does better as a budget drive. Reply
  • KAlmquist - Friday, November 6, 2015 - link

    Yup. I would be excited about the performance of the BX200 if I worked for ADATA. Reply
  • Dritman - Wednesday, November 4, 2015 - link

    This is actually embarrassing, to put this product into today's market, at any price. You cannot step backwards THIS far.

    A crap review is like one of the cheap OCZ drives, except they're understandably bad, because they're so cheap and kinda in line with the price.

    With this thing though, it's much worse than anyone could have imagined.
    Reply
  • bennyg - Tuesday, November 10, 2015 - link

    80mb/s sequential write is not that bad in a SSD. If it were made in 2009. Reply
  • TonyCL6 - Friday, November 6, 2015 - link

    The comparison chart should add Samsung 840EVO (planer 19nm TLC) and ADATA SP550 (planer Hynix 16nm TLC) to be more meaningful. It helps users understand the sustain Seq. write (after pSLC cache ran out) performance differences between planer TLC of Samsung 19nm, Toshiba 19nm, Hynix 16nm and Micron 16nm. Reply
  • Kutark - Sunday, November 15, 2015 - link

    Can someone answer a question for me. It says these are capable of roughly 500MB/s read and write, however SATA3 obviously saturates around 200. Are those figures for m.2 PCIE versions of the drive or? Cus I see them advertised for the 2.5" SATA drives and im a little confused.

    I was about to build a skylake setup as a Christmas gift to myself, however I was looking at some of the NVMe drives etc, to get better perf than SATA3 can offer, however, they're significantly more expensive per GB. So, if I can get something with a sustained 500 read/write like this, (or maybe a "pro" version, i.e. non NVME) I'd rather save the money, as realistically in a gamer situation the difference between 500mb/s and 1000 is gonna be negligible.
    Reply

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