WD Blue SN5000 4TB SSD review: Western Digital launches a 4TB mainstream drive

The WD Blue SN5000 4TB aims at a mainstream audience. Larger-capacity SSDs are always in demand, so new drives that are limited to 2TB often elicit sighs. Game install sizes keep increasing, so where are the less expensive options to really get the most out of that M.2 slot? WD has never been shy in this respect, now offering up to 8TB on its WD Black SN850X, but its popular budget drives have long stopped at the 2TB sweet spot. That changes today, as the Blue SN5000 finally pushes things into 4TB territory with its new BiCS6 QLC flash.

The mention of QLC flash probably elicits sighs of its own. It’s best not to be too hasty, as the performance specifications of this flash rival those of earlier 3D TLC flash generations. It's also paired with mature controller technology, sharing a lineage with popular drives including the WD Blue SN580, WD Black SN770, and diminutive siblings like the WD Black SN770M and OEM WD SN740. In fact, the smaller TLC-based SN5000 SKUs essentially match the SN770, which isn’t a bad thing if they end up being priced competitively. However, the QLC-based 4TB is the star of the show.

We know that BiCS6 flash is efficient from our Sabrent Rocket 4 review, thanks to an updated design. It can also be stacked high with 1Tb dies, made more convenient with denser QLC flash. This means it's possible to relatively easily create a single-sided, cool-running SSD with 4TB of capacity. The WD Blue SN5000 4TB should be a great option for desktops, laptops, and the PS5, but it has to be priced right to fend off competitors. It also doesn’t make the most of its PCIe 4.0 interface — though we’d expect any Black SN7000 model to do so — which makes it feel a bit outdated, PCIe 3.0 hosts notwithstanding. Still, it will be interesting to see how well this QLC flash performs when paired with an optimized SSD platform.

WD Blue SN5000 Specifications

The WD Blue SN5000 comes in 500GB, 1TB, 2TB, and 4TB flavors. Pricing is currently all over the place and likely not set in stone, with the 4TB version we're reviewing today available for around $350 at the time of writing. That's far too expensive, so no doubt the price will come down once supply picks up. WD markets this drive for AI, primarily due to its capacity range, but that seems to just be part of a wider trend to tack "AI" onto product brochures with little meaning to everyday users. It’s not something that should artificially raise the price for this market.

Performance for the drive at up to 2TB, all of which use TLC flash, can reach 5,150 / 4,850 MB/s for sequential reads and writes and up to 650K / 770K IOPS. If this looks familiar, it’s probably because these specifications match the WD Black SN770 almost exactly. The 4TB model, using QLC flash, reaches up to 5,500 / 5,000 MB/s for sequential reads and writes and up to 690K / 900K IOPS. Write IOPS are higher thanks to the four-plane flash, which allows for better scaling, and the controller can also handle a higher bus rate.

The SN5000 supports software encryption and has a five-year warranty with variable TBW. This means the 2TB has a lower TBW than its SN770 counterpart, although this isn’t a dealbreaker. 1,200TB for the 4TB is relatively low as well, but that's in line with the QLC flash being used.

WD Blue SN5000  Software and Accessories

One of the advantages of getting a retail WD SSD is that it will be backed by decent software for minimal fuss. WD offers an OEM version of Acronis True Image for backups and data migration as well as its Western Digital Dashboard. The latter application is an SSD toolbox with full drive and system information, including a clear display of drive health. Drive operations like secure erase and firmware updates are supported.

WD Blue SN5000: A  Closer Look

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The Blue SN5000 comes in the M.2 2280-S3-M form factor, meaning it’s single-sided. This makes the drive a good fit for laptops and other portable devices. On the PCB we see the controller, no DRAM, a power management integrated circuit (PMIC), and two NAND flash packages.

Each package packs 2TB of storage, which with the 1Tb QLC flash means each contains sixteen dies. This is generally the maximum you can stack flash given component height limitations and operational efficiency. We will, however, see 2Tb QLC flash dies in the future.

What's also interesting is that WD could easily put four NAND packages into a single-sided design for an 8TB drive, or with a double-sided configuration 16GB would be achievable. Of course, price would be an even bigger concern with such capacities, but we're seeing 4TB drives starting at around $200, and with four QLC NAND packages we could see far more affordable 8TB models — most still cost upward of $800.

Although the label suggests the drive could reach up to 8-9W of power draw, via SMART the drive’s maximum power state is 6.3W. This is not a drive where power consumption should be a huge concern and, likewise, heat generation should be modest. The drive should work great in any setup.

The 4TB is the most interesting SKU as it’s using hardware we haven’t reviewed before. Specifically, the BiCS6 QLC flash is new. We've seen BiCS6 TLC in the Corsair MP600 Elite and the updated MP600 Mini (E27T), where it proved relatively efficient with good performance. The QLC variant shows promise as well, with the same four-plane design but with higher data density. QLC flash is bound to be slower than TLC flash, though, with 30% higher read latency and only 37.5% of the maximum write performance, but much of this is hidden with pSLC caching and multi-planar optimizations.

This flash, like the TLC variant, is capable of running at up to 2400 MT/s. This is likely why WD uses a different controller on the SN5000, at least at 4TB, than we’ve seen before. Such a controller should be able to get the most out of the PCIe 4.0 interface, like Phison’s E27T controller on the two drives listed above, but WD’s older 16nm platform only reaches 5.5 GB/s here. This might be artificial product segmentation, as we see with the SN770 and Blue SN580, and makes us think of the speed-limited Samsung 990 EVO. Given the similarities of the smaller SN5000 SKUs to the SN770, it’s likely this controller will be used to full effect in the Black SN7000. Luckily for the SN5000, bandwidth is only one aspect of drive performance.

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