The SanDisk X400 is the flagship model of SanDisk's business/OEM SSD lineup. As the successor to the X300 and X300s, the X400 continues the strategy of combining premium features like encryption and a 5-year warranty with the use of cheaper TLC NAND flash to hit mainstream price points.

The SanDisk X400 is intended to be a relatively high-end TLC drive with performance suitable for the mainstream segment of the SSD market that is still predominantly served by SSDs using MLC NAND. SanDisk has had success in the past with developing TLC SSDs such as the Ultra II that perform much better than they typical value-oriented TLC-based SSD.

The X400 adopts the Marvell 88SS1074 SSD controller, a made-for-TLC design with LDPC error correction support that allows for a substantial increase in rated write endurance. The NAND used in the X400 is SanDisk's "sixth generation TLC", manufactured on the 15nm process they share with Toshiba. Carried over from other TLC drives like the Ultra II, the flash in the X400 supports SanDisk's nCache 2.0 SLC caching with on-chip copying of data from the SLC cache to TLC.

Unlike most TLC product lines, the SanDisk X400 provides usable capacities at power of two increments: 128GB through 1024GB, rather than the more common 120GB through 960GB. SanDisk hails the X400 line as including the first single-sided 1TB M.2 SSD - the X300 M.2 only went up to 512GB by comparison. The 2.5" models also use a single-sided PCB, with a large thermal pad interfacing all the flash and DRAM chips and the controller to the metal side of the case.

SanDisk X400 Specifications
Capacity 128 GB 256 GB 512 GB 1 TB
Sequential Read 540 MB/s 540 MB/s 540 MB/s 545 MB/s
Sequential Write 340 MB/s 520 MB/s 520 MB/s 520 MB/s
Random Read IOPS 93.5k 93.5k 93.5k 95k
Random Write IOPS 60k 60k 75k 75k
Form Factors 2.5", M.2 2280
Encryption TCG Opal 2.0 (SED models only)
Write Endurance 72 TB 80 TB 160 TB 320 TB
Warranty 5 years
DWPD Equivalent 0.315 0.175

The SanDisk X300s was the self-encrypting drive variant of the X300, but for the X400 SanDisk is using the same branding on both variants. The self-encrypting drive models have separate SKUs but are still advertised as just SanDisk X400, not X400s. This makes it a little confusing all around and means that users should double check the exact SKU being offered. In the table below, 1122 in the SKU name indicates an individual unit per sale with retail packaging, rather than bulk purchase packaging.

    Self-Encrypting SKU Regular SKU
128 GB M.2   SD8SN8U-128G-1122
SATA SD8TB8U-128G-1122 SD8SB8U-128G-1122 
256 GB M.2   SD8SN8U-256G-1122
SATA SD8TB8U-256G-1122 SD8SB8U-256G-1122 
512 GB M.2   SD8SN8U-512G-1122
SATA SD8TB8U-512G-1122 SD8SB8U-512G-1122
1TiB (1024GB) M.2   SD8SN8U-1T00-1122
SATA SD8TB8U-1T00-1122 SD8SB8U-1T00-1122 

In this review, we are testing the 2.5" 1TB SanDisk X400 model with no TCG Opal encryption support, the SD8SB8U-1T00-1122. The competition and drives to compare against includes the OCZ Trion 150 as one of the best-performing budget TLC SSDs, the Crucial MX200 (a solid mid-range MLC SSD), SanDisk's own high-end MLC-based Extreme Pro, and the Samsung 850 EVO (the 3D TLC SSD that performs like a high-end MLC SSD).

AnandTech 2015 SSD Test System
CPU Intel Core i7-4770K running at 3.5GHz
(Turbo & EIST enabled, C-states disabled)
Motherboard ASUS Z97 Pro (BIOS 2701)
Chipset Intel Z97
Memory Corsair Vengeance DDR3-1866 2x8GB (9-10-9-27 2T)
Graphics Intel HD Graphics 4600
Desktop Resolution 1920 x 1200
OS Windows 8.1 x64
Performance Consistency
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  • Billy Tallis - Friday, May 6, 2016 - link

    I changed TiB to TB. In reality the sizes are only nominal. The exact capacity of the X400 is 1,024,209,543,168 bytes while 1TiB would be 1,099,511,627,776 bytes and 1000GB drives like the 850 EVO are 1,000,204,886,016 bytes.
  • HollyDOL - Friday, May 6, 2016 - link

    yay, that's some black magic with spare areas / crc prossibly...
    X vs Xi prefixes are treatcherous... while with kilo it does only 2,4%, with Tera it's already 9,95%...more than enough to hide OS and majority of installed software :-)
  • bug77 - Tuesday, May 10, 2016 - link

    Then you should put that into the article, unless you're intentionally trying to be misleading ;)
  • SaolDan - Friday, May 6, 2016 - link

  • hechacker1 - Friday, May 6, 2016 - link

    I'm tempted to buy two 512GB and RAID 0 them. Does anybody know if that would improve performance consistency compared to a single 1TB drive? I don't really care about raw bandwidth, but 4k IOPS for VMs. I'm having trouble finding benchmarks showing what RAID 0 does to latency outliers
  • CaedenV - Friday, May 6, 2016 - link

    As someone who has been running 2 SSDs in RAID0 for the last few years I would recommend against it. That is not to say that I have had any real issues with it, just that it is not really worth doing.
    1) once you have a RAID your boot time takes much longer as you have to POST, RAID, and then POST again, then boot. This undoes any speed benefit for fast start times that SSDs bring you.
    2) It adds points of failure. Having 2 drives means that things are (more or less) twice as likely to fail. SSDs are not as scary as they use to be, but it is still added risk for no real world benefit.
    3) Very little real-world benefit. While in benchmarks you will see a bit of improvement, real world workloads are very bursty. And the big deal with RAID with mechanical drives is the ability to que up read requests in rapid succession to dramatically reduce seek time (or at least hide seek time). With SSDs there is practically no seek time to begin with, so that advantage is not needed. For read/write performance you will also see a minor increase, but typically the bottleneck will be at the CPU, GPU, or now even the bus itself.

    Sure, if you are a huge power-user that is editing multiple concurrent 4K video streams then maybe you will need that extra little bit of performance... but for most people you would never notice the difference.

    The reason I did it 4 years ago was simply a cost and space issue. I started with a 240GB SSD that cost ~$250 which was a good deal. Then when the price dropped to $200 I picked up another and put it in RAID 0 because I needed the extra space and could not afford a larger drive. Now with the price of a single 1TB drive so low, and with RAID having just as many potential issues as potential up-sides, I would just stick with a single drive and be done with it.
  • Impulses - Friday, May 6, 2016 - link

    I did it with 2x 128GB 840s at one point and again last year for the same reasons, cost and space... 1TB EVO x2 (using a 256GB SM951 as OS drive) If I were to add more SSD space now I'd probably just end up with a 2TB EVO.

    Probably won't need to RAID up drives to form a single large-enough volume again in the future, this X400 is already $225 on Amazon (basically hours after the article went up with the $244 price).

    I don't even need the dual 1TB in RAID in an absolute sense, but it's more convenient to have a single large volume shared by games/recent photos than to balance two volumes.

    I don't think the downsides are a big deal, but I wouldn't do it for performance reasons either, and I backup often.
  • phoenix_rizzen - Friday, May 6, 2016 - link

    Get 4 of them and stick them into a RAID10. :)
  • Lolimaster - Friday, May 6, 2016 - link

    There's no point in doind raid0 with SSD's. You won't decrease latency/access times or improve random 4k reads (they will be worse most of the time).

    Sequential gains are meaningless (if it matter to you then you should stick to a PCI-e/m.2 NVME drive)
  • Pinn - Friday, May 6, 2016 - link

    I have the Samsung NVME M.2 512gb in the only m.2 slot and am aching to get more storage. Should I just fill one of my PCIe slots (x99)?

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