The Crucial BX300 (480GB) SSD Review: Back To MLC

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.

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.