The WD Blue NVMe SSD is the company's entry-level model with the NVMe interface, which provides much better throughput than the aging SATA standard. While most competing drives use a PCI-Express x4 interface, WD has chosen to stick with a narrower x2 interface, which brings cost savings, but caps maximum transfer rates at about 1.6 GB/s. This isn't a big deal for most applications as our benchmarks show, and a lower peak transfer speed also lets the company use just a single flash chip (providing four channels to the controller). On the controller side, this means a less complex design can be used; it won't have to support eight flash channels like the high-end models do. Last but not least, WD has gotten rid of the DRAM chip, saving a few additional dollars in the process.

The DRAM chip provides caching for the SSD mapping tables, which help the controller keep track of where it put the data. Without it, performance is going to be reduced, and another system that still allows for housekeeping of this important data without compromising on integrity has to be implemented, all while minimizing the performance loss. We tested DRAM-less SSDs in several previous reviews and noticed that this design choice mostly affects random writes that are spread out over a fairly large area. Reads and sequential transfer speeds are nearly unaffected.

Our real-life testing shows that WD has done an excellent job with their new SSD. Averaged over all our real-life tests, the drive keeps up with other affordable entry-level drives, like the Intel 660p, Crucial P1, and the Team Group MP34. The fastest NVMe drives in our test group are 11% faster—not that much. Compared to SATA drives, the performance uplift is around 10%-15%, which can vary greatly by application, too. Looking at synthetics, the WD Blue does well and achieves a good middle spot in the pack. The only weak results are in our random mixed testing, which intermixes writes and reads sent to the drive. It seems that is a scenario WD hasn't optimized its controller for. The other workloads, even random writes, are good and lead me to believe that WD is either using the controller's internal memory for the mapping tables and/or has found a way to work around the performance limitations of DRAM-less designs. We reached out to several contacts in the company and were completely ignored.

Sequential write performance of the drive is good, reaching 744 MB/s when averaged over a longer time. It's sad to see that WD is still clinging to its small pseudo-SLC cache sizes. With 10 GB, that cache is quite small for an NVMe drive, which means writes will start out at a high 1.2 GB/s but drop to around half of that after just a few seconds of full-speed write activity. Other vendors include bigger SLC caches with their drives, which helps them soak up larger write bursts.

Thermal performance of the WD Blue is excellent. We didn't observe any thermal throttling no matter the load we threw at the completely uncooled drive. This hints at a well optimized design that can do without a heatspreader. Limiting the interface to x2 has also helped with this, just like the small SLC cache, which won't allow longer write bursts to happen in the first place.

Overall, with a price of $73 for the tested 500 GB version, the WD Blue is an excellent deal in the entry-level NVMe market, but doesn't do significantly better than other options at similar pricing. While I would definitely pick it over any similarly priced QLC drive, I'd still go for an SSD with DRAM, as that ensures optimum performance in even edge cases. Looking at the SN500 design, I think WD still has quite a good margin left in it, so I wouldn't be surprised to see it at even lower pricing soon, well below $70.

Good SATA SSDs like the Crucial MX500 are $70 for 500 GB at the moment, with some value-oriented models like the BX500 even reaching $60. Compared to the WD Blue, both of those options offer lower performance with only little money saved—I'd go for an NVMe drive any day, for higher performance and the more compact form factor. Only when every dollar counts, with mostly light read-heavy workloads would it make sense to still opt for a SATA SSD. WD includes a generous five-year warranty, and the company's top-notch reputation could also be a reason to choose it over smaller competing vendors.