Conclusion
With the Crucial MX300, you have to take the good with the bad. There are several points to consider, and the pro's and cons each have several items that give us a full picture of the overall drive.
Let's start at the SSD controller, which is the heart of the system. The controller sits between the SATA bus and the NAND. The Marvell 88SS1074 "Dean" utilizes four channels but also features Low-Density Parity Check (LDPC) to extend the life of the flash. This is the first time Crucial has used a 4-channel controller in a mainstream class MX Series SSD. Some of the older, smaller capacity drives only used four channels, but they still shipped with 8-channel controllers. 4-Channel controllers are cheaper to design, manufacture and use less power. They are also slower than true 8-channel controllers are and limit scale-out (addressing a large number of NAND die) and parallel IO.
When Micron announced the first generation 3D NAND, we learned that it doubled the density of MLC and tripled the density of TLC. At first, that sounded great! Until now, vendors based SSD pricing on how much space each die consumed on the wafer and the number of NAND die in the drive. When IMFT moved from 25nm to 20nm, the retail SSDs experienced a large price reduction. The same thing happened from 20nm to 16nm. Historically, you could go back, examine pricing data, and easily spot when a new lithography shrink came to market. If that were true with the new 3D NAND, the Limited Edition 750GB would cost about 80 Dollars rather than 185. IMFT is likely recouping some of the expensive R&D investments early on, and the current NAND flash shortage helps to keep prices high right now, too.
When it comes to 3D NAND's performance, the updated ONFI interface increases the flash's bandwidth through the interface back to the controller. At that critical link in the chain, Micron's new 3D is faster than any flash it had before. The increased ONFI bandwidth is the primary reason why Crucial was able to use a 4-channel controller in a mainstream SSD.
The faster interface speed is nice, but it still doesn't deliver the 500+ megabytes per second we get with these products. Micron's 3D NAND uses quad planes, and that means your data has four paths off the die instead of just one, but that still doesn't add up to 500+ MB/s. For that, you need massively parallel operations, which means reading and writing to a large number of die simultaneously. Due to the 3x increase in die density to 384Gb (48GB), the MX300 will not show us what Micron's 3D NAND is really capable of until we see the 2TB model next month.
Crucial used twenty-four die to hit 1152GB of raw NAND capacity. The 1050GB model we tested today looks really good considering the number of die used to reach the capacity point. In contrast, the Samsung 850 EVO 500GB uses thirty-two NAND die in tandem with an efficient 8-channel controller. The two SSDs deliver nearly identical performance outside of the low QD random read tests.
The MX300 525GB uses just twelve NAND die, but it compares well to the 850 EVO 500GB, too. The Dynamic Write Acceleration helps both MX300 SSDs stay competitive even when, on paper, they shouldn't. The MX300 750GB was a little rushed, and Crucial really should have held it until the firmware was as mature as it is now with the two new models we tested. The underlying technology in combination with the newer firmware makes the MX300 SSDs more attractive than we initially expected.
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