We tested the RD400 on both the bundled x4 PCIe adapter and the M.2 PCIe slot integrated on our test motherboard. Performance was very consistent in AS SSD’s 10GB test, but there were variances of several hundred MBps in the 1GB test from run to run. We’re guessing that the cause is the beta driver used for testing, but it could be caching techniques. Regardless of the reason, it’s still a very fast drive.
Part of the performance magic of SSDs is being able to write via multiple paths to multiple chips. We tested the 512GB version of the RD400, which can reach 2.1GBps for read speed and 1.3GBps for write speed. The 1TB version is rated for the same. However, the 128GB version of the RD400 is rated for half of that write speed, and the 256GB version about three-quarters. They read at roughly the same speeds as their larger siblings.
Toshiba is notoriously reticent about providing information on the controller and NAND—but my guess is the NAND is either MLC, or TLC being treated as such.
Warranty and price
All flavors of the RD400 carry a warranty of five years and 74TBW (terabytes written) for every 128GB of capacity. Rumor has it that this drive should exceed that estimate, but even if it doesn’t, that rating’s still on par with competing drives.
NVMe drives still cost quite a bit more than SATA models, but given the tripled speed, it’s a relatively small price to pay. The 128GB version of the RD400 is $110 (86 cents per GB), the 256GB version is $170 (66 cents per GB), the 512GB version $310 (61 cents per GB), and the 1TB version $740 (77 cents per GB). Add $20 to those prices if you want the version of the drive that comes with the PCIe adapter we used during testing.
If your system supports NVMe, spend the money. Yes, if you opt for a normal SATA SSD, you’ll be pleased. But if you opt for an NVMe SSD, you’ll be amazed. It really is the best performance upgrade you can buy, bar none.
As far as the RD400 is concerned, stick with 256GB capacity or better, unless you’re truly strapped for cash. The 512GB version is the sweet spot in price-per-gigabyte and also offers the best performance.
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