Western Digital

WD_BLACK SN850

Expert rating7.8 / 10

Model:: WD_BLACK SN850
Interface:: PCIe 4.0
Sequential Read:: Up to 7
Heatsink Option:: Available

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Manufacturer: Western Digital Last updated: September 12, 2026

WD_BLACK SN850 (PCIe 4.0 NVMe/7,000 MB/s Read/5,300 MB/s Write/Original Gen4 Flagship, Pre-X) Review

The WD_BLACK SN850 was Western Digital's original PCIe 4.0 flagship before the SN850X replaced it, and it's still sold and still worth buying when it's discounted below the newer drive.

It uses WD's in-house SanDisk-made controller and TLC NAND, and the numbers (7,000 MB/s read, 5,300 MB/s write) were class-leading in 2020 and remain more than fast enough for gaming and everyday use today. Buy this over the SN850X only when it's meaningfully cheaper; otherwise the newer drive's better sustained write performance is worth the difference.

Performance and Speed

7,000 MB/s sequential read and 5,300 MB/s write were genuinely flagship numbers at launch, and while the newer SN850X and Samsung 990 PRO have since pulled ahead on sustained writes and thermal management, the base SN850 still comfortably outruns anything a game or a Windows boot drive actually needs day to day.

Where It Sits Today

Western Digital kept this drive in production and pricing alongside the SN850X rather than discontinuing it outright, so it now functions as the value option in WD's own lineup, a step below the SN850X's improved controller and flash but a real step above the DRAM-less SN770 covered elsewhere on this site.

Comparison to Sibling Products

Against the WD_BLACK SN850X, also covered on this site, the X model uses a refreshed controller and newer flash that hold up better under long sustained writes and run slightly cooler; buy the SN850X first unless this drive is on a clear discount. Against the WD_BLACK SN770, this drive's DRAM cache makes it meaningfully better for large file transfers and game installs, where the DRAM-less SN770 can slow down.

Who This SSD Is Actually For

Buyers who find this drive discounted below current SN850X pricing. The performance gap in real gaming use is small enough that the savings usually win.

PS5 owners who already have the heatsink-equipped SKU on hand. It meets Sony's expansion slot requirements just as well as the newer drive.

Not for buyers doing frequent large sustained writes at full retail price. The SN850X's updated controller handles that workload with less slowdown, covered elsewhere on this site.

Specifications

Identity

Brand	Western Digital
Model Number	SN850
Series	WD_BLACK SN850

Interface and form

Drive Type	Internal
Bus Interface	PCIe 4.0 x4, NVMe
Bus Interface	PCIe 4.0 x4
Form Factor	M.2 2280

Sequential performance

Sequential Read	7000 MB/s
Sequential Write	5300 MB/s

Controller and cache

DRAM Cache	DRAM

NAND

NAND Type	TLC with DRAM Cache

Power and thermals

Heatsink	Available

Physical and commercial

Warranty	5 Years

Capacity Options	500GB, 1TB, 2TB, 4TB

Expert Review

Reviewed by Burooj Alam. Rated by us, not by users.

Expert rating7.8 / 10

A genuinely strong PCIe 4.0 drive that's been surpassed by its own successor. Buy it on sale, not at full price next to the SN850X.

Best for

Buyers who find this drive discounted below current SN850X pricing. The performance gap in real gaming use is small enough that the savings usually win.
PS5 owners who already have the heatsink-equipped SKU on hand. It meets Sony's expansion slot requirements just as well as the newer drive.
Anyone upgrading from SATA who doesn't need the absolute latest controller generation. Even at four generations old in NVMe terms, this drive is a massive step up.

Not for

Not for buyers doing frequent large sustained writes at full retail price. The SN850X's updated controller handles that workload with less slowdown, covered elsewhere on this site.
Not for anyone who can find the SN850X at the same price. There's no scenario where SN850 beats SN850X except cost.
Not for PCIe 5.0 builds wanting to use the full bandwidth of a new motherboard. This is a Gen 4 drive through and through.

FAQs

What are the key specifications of the WD_BLACK SN850 (PCIe 4.0 NVMe/7,000 MB/s Read/5,300 MB/s Write/Original Gen4 Flagship, Pre-X)?

The WD_BLACK SN850 (PCIe 4.0 NVMe/7,000 MB/s Read/5,300 MB/s Write/Original Gen4 Flagship, Pre-X) is a component from Western Digital. Key specs: Interface PCIe 4.0 x4, NVMe, Sequential Read 7000, Sequential Write 5300, NAND Type TLC with DRAM Cache, Capacity Options 500GB, 1TB, 2TB, 4TB.

Who is the WD_BLACK SN850 (PCIe 4.0 NVMe/7,000 MB/s Read/5,300 MB/s Write/Original Gen4 Flagship, Pre-X) best suited to?

It suits buyers who find this drive discounted below current sn850x pricing. the performance gap in real gaming use is small enough that the savings usually win., ps5 owners who already have the heatsink-equipped sku on hand. it meets sony's expansion slot requirements just as well as the newer drive., anyone upgrading from sata who doesn't need the absolute latest controller generation. even at four generations old in nvme terms, this drive is a massive step up..

What are the drawbacks of the WD_BLACK SN850 (PCIe 4.0 NVMe/7,000 MB/s Read/5,300 MB/s Write/Original Gen4 Flagship, Pre-X)?

It is a poor fit for not for buyers doing frequent large sustained writes at full retail price. the sn850x's updated controller handles that workload with less slowdown, covered elsewhere on this site., not for anyone who can find the sn850x at the same price. there's no scenario where sn850 beats sn850x except cost., not for pcie 5.0 builds wanting to use the full bandwidth of a new motherboard. this is a gen 4 drive through and through..