WD Black SN850X with Heatsink 2TB SSD Review

1. Introduction2. WD Black SN850X + Heatsink3. Testing Methodology4. CrystalDiskMark5. ATTO Disk Benchmark6. AS SSD7. 128KB Sequential Performance8. 4K Random Read v QD Performance9. 4K Random Write v QD Performance10. 4K 70/30 Mixed Performance11. 4K Random Performance QD1-QD812. Throughput13. PCMark 10 Full System Drive Benchmark14. 3DMark Storage Benchmark 15. Performance Stability16. Temperatures17. Real Life File Testing18. Closing Thoughts19. View All Pages

WD's first PCIe Gen 4 drive, the very popular WD Black SN850, was and still is a very quick drive. But it was launched nearly two years ago, which in the Gen 4 drive market space, seems like an eternity. But now we have its successor for the fastest WD drive crown, the Black SN850X. WD are in the fortunate position to have all three parts of the component jigsaw; NAND, controller and cache chip available in-house so once again we have a WD controller, cache and 3D NAND. Instead of the BiCS4 96-layer that the Black SN850 used we have shiny new BiCS5 112-layer 3D TLC NAND in the Black SN850X.

At the time of writing this review, details on the SN850X's controller are pretty non-existent. If it is one of WD's in-house G2 controllers (that powers the SN850 as well as the SN770) it will probably have had updates made to the firmware to cater for the more advanced NAND in the SN850X. All we can say for certain is that the product codes on the controller for the SN850/SN770 are different to the SN850X; 20-82-10034-A1 and 20-82-20035-B2 respectively.

As with the Black SN850, the Black SN850X is available in three capacities, but it does way with the SN850's 500GB entry drive and instead has a 1TB entry drive along with 2TB and 4TB models. There are two versions of the drive, a plain one and a heatsink version, which is only available (at the time of writing) in the smallest two capacities. The heatsink version has RGB lighting but it is very subtle as the area for the lighting is only around 12mm x 3mm and only supports three of the thirteen lighting effects provided in the SSD Dashboard utility. Choosing the heatsink version over the vanilla drive will take around an extra tenner or so out of your budget.

WD quote Sequential read/write figures for the 2TB SN850X as up to 7,300MB/s and 6,600MB/s respectively which is a healthy 300MB/s and 1,500MB/s rise in read and writes respectively over the 2TB Black SN850. Incidentally, that 7,300MB/s read figure is the same for all three drives in the range. When it comes to Sequential writes the 4TB model gets the 6,600MB/s rating as does the 2TB drive with the 1TB drive rated as up to 6,300MB/s.

Using the ATTO benchmark we couldn't match those maximums, the tested drive producing a read figure of 6,820MB/s and a write figure of 6,230MB/s. However, switching over to the CrystalDiskMark 8 benchmark we could indeed confirm the official maximums with test results of 7,377MB/s (default-test) and 6,696MB/s (0 fill) for read and writes respectively.

As for random read performance, WD quote an up to 1,200,000 IOPS figure for the 2TB drive with random writes rated as up to 1,100,000 IOPS. Both are an improvement over the 2TB Black SN850 figures of 1,000,000 IOPS for reads and 710,000 IOPS for writes.

We couldn’t get close to these figures with our 4-threaded tests. The best read figure we saw was 446,377 IOPS. We then retested the drive at a QD of 32 and with 8 threads which resulted in a figure of 648,467 IOPS, closer to the official figure but no cigar. The fastest performance we saw from the drive came when using the Peak Performance profile (0 fill) in CrystalDiskMark 8 with a test result of 743,828 IOPS.

Random writes came up short in our tests as well. Our 4-threaded test yielded 362,876 IOPS at a queue depth of 32. Staying at the same queue depth but increasing the thread count to 8 saw the resulting figure rise to 464,466 IOPS. Again the fastest performance came via CrystalDiskMark 8's Peak Performance profile with a test result of 602,168 IOPS.

The drive is also supported by the very good WD SSD Dashboard management software.  A pretty comprehensive utility, SSD dashboard  allows you to monitor drive status, and performance, perform secure erases (currently only by making a bootable USB device), update firmware and monitor temperatures. The latest version of the utility includes the updated Gaming Mode 2.0. When turned on, the firmware disables the power-saving features that are incorporated into the drive allowing lower latencies and more performance. The one annoying aspect of this Gaming Mode is that you have to restart the system to enable/disable it.

The jury is out on the Game Mode 2.0, to be honest. When we tested the drive with 3D Mark's Storage Test we didn't see that much difference whether it was turned on or off. It's early days for the feature and hopefully, with time it should make more of an impact.

We found the 2TB version of WD's Black SN850X Heatsink on Overclockers UK for £329.99 (inc VAT) HERE.

Pros

• Stunning performance.
• Heatsink.
• WD Dashboard management utility.
• 5-year warranty.

Cons

• Couldn't hit the maximum 4K figures under testing.
• Pricey.

KitGuru says: WD's Black SN850 drive was already a very good flagship drive but with an upgrade from 96-layer to 112-layer NAND and improvements to the firmware, the SN850X takes over that mantle with great effect. But the price could do with some tweaking.

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