Pros & Cons
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- Exceeded its Crystal DiskMark sequential read and write speed ratings
- Excellent 4K read benchmark results
- Above-par PCMark 10 Overall and 3DMark 10 scores
- Energy-efficient architecture
- Includes downloads for Acronis True Image and Sandisk Dashboard software
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- Relatively low TBW (durability) rating
- Low 4K write test results
- Lacks heat spreader or heatsink
- Doesn't support hardware-based encryption
WD Blue SN5100 Specs
| Bus Type | PCI Express 4.0 |
| Capacity (Tested) | 2 |
| Controller Maker | SanDisk |
| Interface (Computer Side) | USB-C |
| Internal Form Factor | M.2 Type-2280 |
| Internal or External | Internal |
| NAND Type | QLC |
| NVMe Support | |
| Rated Maximum Sequential Read | 7100 |
| Rated Maximum Sequential Write | 6700 |
| Terabytes Written (TBW) Rating | 900 |
| Warranty Length | 5 |
Sandisk's WD Blue SN5100—a DRAM-less PCI Express 4.0 internal SSD with QLC NAND flash memory—has a lot of strong points. It performed well in our testing, especially in our general-storage and gaming-centric benchmarks, and also comes with a free download of Acronis backup and migration software. But the picture isn't all rosy in our tests. Even though it's energy efficient, the SN5100 ships without a heatsink or heat spreader. And it conforms to the TCG Pyrite security standard, which doesn't support AES hardware-based encryption. So, the SN5100 doesn't unseat the Crucial T500 as our Editors' Choice, but it is well worth considering if you can find it at a good price.
One small note before I get into the review: As I detailed in my write-up of the WD Black SN8100 early this year, Western Digital spun off SanDisk (capital "D") into an independent, lowercase-"D" public company, Sandisk. (WD still owns a stake.) The new company handles WD's NAND flash-memory-based products, including SSDs, leaving WD to focus on the hard drive segment. At least for now, their SSDs still bear WD branding and are imprinted with both the WD and Sandisk names.
Design and Specs: NAND Without DRAM
The SN5100 is built in the M.2 Type-2280 "gumstick" form factor common among today's internal SSDs. In terms of tech, it uses the NVMe 2.0 protocol over its PCI Express (PCIe) 4.0 bus, as well as Sandisk's own 218-layer BiCS8 quad-level cell (QLC) 3D NAND flash and a Sandisk Polaris 3 controller. (Baffled by some of these terms? Check out our glossary of SSD terminology.)
(Credit: Joseph Maldonado)The Polaris 3 controller lacks its own dynamic random access memory (DRAM), instead relying on the computer's host memory buffer (HMB) for caching. DRAM-less SSDs tend to consume less power and run cooler than SSDs with their own DRAM cache, and they come in at a lower price, to boot. This sounds good, but lots of people fear that this architecture impacts write speeds in certain scenarios—a fear that seems to be borne out in the SN5100's case. More on that below.
(Credit: Tony Hoffman)The SN5100 lacks either a heatsink or heat spreader; its low power consumption should minimize heat buildup and reduce the chances of thermal throttling, but we still recommend the use of a heatsink whenever possible with PCI Express 4.0 and 5.0 SSDs. Many desktop motherboards, of course, will have heat spreaders included and installed over one or more M.2 slots, so this may be a non-issue for you.
Capacity and Pricing: Up to 4TB, Upscale Price and Performance
The WD Blue SN5100 comes in four capacities, ranging from 500GB to 4TB. Its pricing, based on both list and retail costs, is in the upper tier for a QLC-based and/or DRAM-free PCIe 4.0 SSD. Still, it's not exorbitant, especially given its performance (as we'll see shortly).
Solid-state drives based on QLC NAND flash memory tend to be less durable for heavy write activity than either TLC or MLC models. You can see that in their lower terabytes written (TBW) ratings, a manufacturer's estimate of how much data can be written to a drive before some cells begin to fail and get taken out of service. That said, the SN5100's durability is good for a QLC stick, better than many of its peers. For example, the Sabrent Rocket Q4 is rated at 200TBW for its 1TB model, 400TBW for 2TB, and 800TBW for 4TB. The Crucial P310 is pegged at 220TBW for 1TB and 440TBW for 2TB, while the Corsair MP600 Core XT comes with a rating of 250TBW for 1TB, 450TBW for 2TB, and 900TBW for 4TB.
Still, once you get above 1TB, the SN5100's durability is low compared with drives using TLC NAND; at 2TB, many TLC sticks have TBW ratings of around 1,200. Durability ratings for some elite TLC drives are even higher. The ADATA Legend 850, for instance, is rated at 1,000TBW (1TB) and 2,000TBW (2TB), and TeamGroup's TLC-based MP44 comes in at 1,450TBW for 1TB, 2,500TBW for 2TB, 3,000TBW for 4TB, and 6,000TBW for its 8TB stick.
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Sandisk provides users with warranty coverage for five years, or until you hit the rated TBW figure in data writes, whichever comes first. But unless you are writing very large amounts of data to the SN5100, it is unlikely to fail during its warranty period.
(Credit: Joseph Maldonado)The SN5100 comes with a free download of Acronis True Image backup and migration software. You can also download the Sandisk Dashboard utility, which allows you to monitor the health of your drive and update the firmware. For data security, the SN5100 supports the TCG Pyrite 2.01 specification for drive access control and some other functions, but it does not provide hardware-based drive encryption.
Performance Testing: Strong Results (With a 4K Falter)
We test PCIe 4.0 internal SSDs using a desktop testbed with an MSI X570 motherboard and AMD Ryzen CPU, 16GB of Corsair Dominator DDR4 memory clocked to 3,600MHz, and a discrete Nvidia GeForce graphics card. We put the WD SN5100 through our usual suite of solid-state-drive benchmarks, comprising Crystal DiskMark 6.0, PCMark 10 Storage, and 3DMark Storage. For comparison, we tested other PCI Express 4.0 SSDs with elite throughput speeds similar to the SN5100's, as well as the Samsung SSD 990 EVO, our favorite budget PCIe 4.0 internal SSD.
Crystal DiskMark's sequential speed tests provide a traditional measure of drive throughput, simulating best-case, straight-line transfers of large files. On these tests, the SN5100 did well, easily exceeding its sequential read-speed rating and topping its rated write speed. Its results put it squarely among the elite PCIe 4.0 speedsters. Then came a stumble: the Crystal DiskMark's 4K read and write tests, which measure how long it takes for an SSD to access or save a group of files in 4K cluster sizes. Things started out well, with the SN5100 posting the best 4K read score among our group of comparison drives. But its 4K write score was the slowest, also by a substantial margin.
The SN5100 got back on track with the PCMark 10 Overall Storage test, which measures a drive's speed in performing a variety of routine tasks such as launching Windows, loading games and creative apps, and copying both small and large files. While SSD manufacturers like to tout their drives' raw speed (sequential read and write scores), we consider PCMark 10 Overall our best gauge of general storage aptitude.
The SN5100's Overall score was one of the best in our comparison group, just 1% behind the Crucial T500 and Teamgroup MP44, which were tied for the top spot.
Finally, in the gaming-centric 3DMark Storage benchmark, the SN5100's score was the second-highest, with the WD Black SN850X turning in a 4% better score. All in all, the SN5100 performed very well on our benchmarks; the low Crystal DiskMark 4K write score was its only real blemish.
Final Thoughts
WD Blue SN5100
Sandisk's WD Blue SN5100, a DRAM-less PCIe 4.0 internal SSD with QLC NAND, showed strong performance on most of our benchmarks. It's also designed for energy efficiency (but ships without a heatsink or heat spreader). It's well worth considering if the price is right.