Once upon a time, I sat with a company questioning them as to why they were so hesitant to market a 1TB SSD; they wouldn’t push that 512GB barrier. Their honest and frank response was simply, “Why sell very few of a product that costs more to build when we can sell much more of what is in demand at a better price?” They were right but that view had to change. Even today, capacities have grown in SSDs but that 8TB barrier is a line in the sand few have crossed. We have reviewed only one other companies 8TB SSDs and that was the Sabrent Rocket Q Gen 3 8TB SSD in 2020, followed by their Gen4 upgrade of the Rocket 4 Plus back in 2022.
On our bench today is the WD_Black SN850X Gen 4 8TB NVme SSD and, even though we have been running that Sabrent Rocket 4 Plus in our main Test Bench for a few years now, there is simply no way we would compare the two side by side. The SN850X is simply the biggest and baddest on the block and its high capacity doesn’t mean performance has to be a trade off. This SSD is as speedy as they come…and it’s game loading times are through the roof. Let’s take a look…
The SN850X is a PCIe 4.0 x4 (four channel) NVMe 2.0 M.2 2280 (22mm wide x 80mm long) SSD that is a available in 1,2,4 and 8TB, but the 8TB differs slightly. It is based on the newest WD TLC 3D BiCS 6 NAND flash memory and whereas the other capacities are based on the slightly faster former 112-layer 3D TLC BiCS 5 NAND, which had been upgraded from BiCS 4 previously. Why does the SN850X have different memory in its newest configuration? BiCS 6 has 162-layers with a resulting 40% smaller footprint. This is the only way we were fitting 8TB on the 850X without running into other complications such as heat…
The WD_Black 8TB SN850X contains a SanDisk in-house Gen 4 8-channel SSD controller and has listed specifications of 7200MB/s read and 6600MB/s write with up to 1.2 million read and write IOPS. It also contains a DDR4 DRAM chip and comes with a 5-year limited warranty with a guaranteed 4800TBW (terabytes written).
Left to right, we have the SanDisk controller on the far left, DRAM package and two BiCS6 NAND chips on the far right. Only because we are using BiCS 6, each module has a capacity of 2TB RAW storage value, with two other NAND chips on the reverse.
This SSD may have an advertised capacity of 8TB but in all actuality, it only provides for 7.4GB of usable storage when formatted. This is normal and typical with all SSDs today, the reasoning having to be the result of firmware and over-provisioning requirements that provide for continued high performance and a lengthy lifespan.
Checking Amazon, we can see pricing for the WD_Black SN850X 8TB SSD to be $899 without the included heatsink and, well at the time of writing this report in any case, the version with the PS5 compatible heatsink is actually $20 less at $879. I know which one I would be grabbing.
Now let’s check out some speeds…