WD Black SN770 1TB — DRAM-less PCIe 4.0 NVMe SSD Review

Posted on May 17, 2026 by Raymond Chen

The WD Black SN770 1 TB is a DRAM-less PCIe 4.0 drive that uses Western Digital's in-house SanDisk controller to punch above its weight class, delivering Gen4 read speeds without the cost of an onboard DRAM cache.

WD Black SN770 1TB — DRAM-less PCIe 4.0 NVMe SSD Review

The SN770 is built around a proprietary SanDisk four-channel PCIe 4.0 x4 controller, paired with BiCS5 112-layer TLC NAND — both designed and manufactured within the Western Digital / Kioxia joint venture ecosystem. Critically, the drive is DRAM-less: it relies on Host Memory Buffer (HMB) version 2.0 to borrow up to 128 MB of system RAM for the flash translation layer, a larger allocation than the 64 MB typical of first-generation HMB implementations. WD's firmware tuning for this controller is the differentiator — independent reviews consistently find the SN770 outperforms other DRAM-less Gen4 drives on sustained random I/O, closing the gap with entry-level DRAM-equipped alternatives.

The 1 TB variant sits in the middle of the SN770 stack, between the 250 GB and 500 GB models below and the 2 TB flagship above. Capacity scaling affects the smaller drives: the 250 GB model drops to 4,000 MB/s reads and 2,000 MB/s writes, while the 500 GB manages 5,000 MB/s reads and 4,000 MB/s writes. The 1 TB variant delivers the full 5,150 MB/s read and 4,900 MB/s write ceiling, sharing peak throughput with the 2 TB model. Endurance scales from 200 TBW on the 250 GB to 1,200 TBW on the 2 TB, with the 1 TB landing at 600 TBW — a 600-TBW-per-terabyte ratio consistent with WD's consumer TLC drives. The drive uses a single-sided M.2 2280 PCB with no factory heatsink, which keeps it compatible with thin notebooks but means sustained write thermals are entirely dependent on ambient airflow or a motherboard M.2 cover.

In the mid-range PCIe 4.0 segment, the SN770 competes against the Samsung 980 (non-Pro), Crucial P5 Plus, and Solidigm P44 Pro at the lower capacity tiers. The SN770's DRAM-less design puts it at a theoretical disadvantage against DRAM-equipped competitors, but WD's firmware and the HMB 2.0 implementation narrow the gap enough that the SN770 is often the fastest DRAM-less drive in its class. For a gaming PC or a general-purpose desktop, the performance difference between the SN770 and a DRAM-equipped alternative like the P5 Plus is perceptible only in benchmarks. For sustained mixed-I/O server or workstation workloads, a DRAM-equipped drive remains preferable.

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🚀 Performance and benchmarks

WD rates the 1 TB SN770 at 5,150 MB/s sequential reads and 4,900 MB/s sequential writes, with random IOPS of 650,000 read and 800,000 write. These figures place it near the top of the DRAM-less PCIe 4.0 class and within reach of entry-level DRAM-equipped drives like the Samsung 980.

Performance comparison

Western Digital Black SN770 1 TB vs M.2 4.0 x 4 peers

Switch between sequential throughput and random IOPS to see how this drive stacks up against other M.2 4.0 x 4 SSDs in our database. The highlighted bar is the drive on this page — click any other bar to open that drive.

PNY XLR8 CS3140 1 TB: 7,500 MB/s read, 5,650 MB/s write
PNY XLR8 CS3140 2 TB: 7,500 MB/s read, 6,850 MB/s write
Asgard AN4 512 GB: 7,500 MB/s read, 5,500 MB/s write
Asgard AN4 1 TB: 7,500 MB/s read, 5,500 MB/s write
Western Digital Black SN770 1 TB (this drive): 5,150 MB/s read, 4,900 MB/s write

WD's nCache 4.0 technology — essentially a large pseudo-SLC write cache implemented in firmware — is the key to the SN770's strong showing in benchmarks. On the 1 TB model, the cache absorbs roughly 100–150 GB of burst writes at full speed before filling, after which native TLC write speeds settle around 800–1,000 MB/s. This is a substantial cache for a DRAM-less drive and means the vast majority of consumer write bursts — game installs, OS updates, file transfers from a USB drive — never encounter the post-cache TLC speed. HMB 2.0's larger 128 MB system RAM allocation, combined with WD's firmware optimisations, gives the SN770 random I/O latency characteristics closer to a DRAM-equipped drive than any previous DRAM-less design. Independent reviewers consistently measure PCMark 10 storage scores within 5% of the Samsung 980 Pro for typical consumer workloads, a remarkable result for a DRAM-less drive. Gaming load times are indistinguishable from any PCIe 4.0 drive — DirectStorage titles and open-world games stream assets fast enough that the SN770 never becomes a bottleneck.

🖥️ Endurance and warranty

WD backs the Black SN770 1 TB with a five-year limited warranty, bounded by a 1,200 TBW endurance rating as recorded in the database — though the standard WD specification for the 1 TB SN770 is 600 TBW, with 1,200 TBW reserved for the 2 TB model. At 600 TBW and a typical 30 GB/day workload, the endurance budget spans roughly 55 years of consumer use. The 250 GB model carries 200 TBW, the 500 GB 300 TBW, and the 2 TB 1,200 TBW. WD's warranty service is handled through the SanDisk/WD RMA portal, with shipping labels provided in most regions and generally faster turnaround than smaller SSD vendors can manage. The drive carries the standard 1.75-million-hour MTBF rating common to WD's consumer NVMe products.

📊 Specs

Category	Value
Capacity [?]	1 TB
Interface [?]	M.2 4.0 x 4
Controller [?]	SanDisk
Memory type [?]	TLC
DRAM [?]	n/a
Read speed (MB/s) [?]	5150
Write speed (MB/s) [?]	4900
Read IOPS [?]	650000
Write IOPS [?]	800000
Endurance (TBW) [?]	1200
MTBF (million hours) [?]	n/a
Warranty (years) [?]	5

Conclusion

The WD Black SN770 1 TB is the DRAM-less drive for people who do not want to think about whether their SSD has DRAM. WD's firmware and HMB 2.0 implementation close the gap with DRAM-equipped competitors to the point of irrelevance for gaming and general desktop use, and the 5,150 MB/s reads are more than sufficient for any consumer workload. Buyers running sustained mixed-I/O workloads — database servers, compilation farms, 8K video ingest — should still choose a DRAM-equipped drive, as should anyone who simply wants the peace of mind that comes with dedicated cache hardware. For everyone else, the SN770 is a fast, efficient, single-sided NVMe drive that consistently outruns its DRAM-less label. The 1 TB capacity is the sweet spot: it delivers the full speed ceiling and enough room for an OS plus a reasonable game library without stepping up to the 2 TB price point.

+ Pros

5,150 MB/s reads — competitive with entry-level DRAM-equipped Gen4 drives
SanDisk in-house controller with HMB 2.0 — more system RAM, better latency
Single-sided M.2 2280 — fits thin laptops without clearance issues
Five-year warranty backed by Western Digital's established RMA process
Excellent sustained TLC write speeds (~800 MB/s) after SLC cache exhausts

- Cons

DRAM-less — sustained mixed I/O trails DRAM-equipped competitors
No factory heatsink — relies on ambient airflow or motherboard cooling
PCIe 4.0 ceiling is mid-pack — Gen4 flagships reach 7,000+ MB/s
250 GB and 500 GB variants are meaningfully slower — check capacity before buying

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✨ Video Review

How can it be this good? WD_BLACK SN770 NVMe SSD 1TB Review

⁉️ FAQ

The SN770 1 TB is an excellent gaming drive. Its 5,150 MB/s reads are more than any current game engine can saturate, and DirectStorage-compatible titles benefit from the consistently low latency of WD's tuned HMB 2.0 implementation. Game loads, level transitions, and texture streaming are indistinguishable from a DRAM-equipped PCIe 4.0 flagship in real-world use — any difference exists only in benchmark charts. The 1 TB capacity fits a healthy game library alongside the OS, and the drive's strong sustained write performance means even large Steam installs complete quickly. For a gaming-only or gaming-primary PC, the SN770 is one of the best value picks in the PCIe 4.0 segment.

No, the SN770 is a DRAM-less SSD. Instead of a dedicated DRAM chip on the PCB, it uses Host Memory Buffer (HMB) version 2.0 to borrow up to 128 MB of system RAM for the flash translation layer. This is a larger allocation than the 64 MB typical of first-generation HMB designs like the Phison E13T and E21T. The combination of HMB 2.0 and WD's proprietary firmware optimisation means the SN770 closes much of the random I/O latency gap versus DRAM-equipped drives — enough that for gaming, productivity, and general desktop use, the difference is not perceptible. Sustained mixed read-write server workloads remain the domain of DRAM-equipped drives.

The SN770 uses a PCIe 4.0 x4 M.2 2280 interface and a single-sided PCB, so it physically fits the PS5 expansion bay. However, its 5,150 MB/s sequential read speed is slightly below Sony's recommended 5,500 MB/s minimum. The PS5 will recognise the drive but may display a performance warning for PS5-native titles. For guaranteed PS5 compatibility, the WD Black SN850P or SN850X — rated at 7,000+ MB/s — is the recommended alternative within WD's own lineup. The SN770 also ships without a heatsink, and Sony requires an M.2 heatsink meeting specific dimensional constraints.

The WD Black SN770 1 TB endurance rating depends on which specification sheet you reference. Industry-standard sources list it at 600 TBW, which translates to roughly 329 GB of writes per day over the five-year warranty. The 2 TB model carries 1,200 TBW. At a typical consumer write rate of 20–30 GB/day, the 600 TBW budget lasts roughly 55–82 years. The 250 GB and 500 GB models carry 200 TBW and 300 TBW respectively. The SN770 uses BiCS5 TLC NAND in a DRAM-less configuration, and the TBW rating is consistent with WD's consumer TLC warranty policy.

Both are DRAM-less PCIe 4.0 drives targeting the mid-range segment, and they are each other's closest competitor. The Samsung 980 1 TB is rated at 3,500/3,000 MB/s read/write — effectively PCIe 3.0 speeds on a Gen4 interface — versus the SN770's 5,150/4,900 MB/s, giving WD a clear throughput advantage. The 980 counters with Samsung's mature in-house controller and generally better sustained random I/O under heavy mixed loads. In real-world consumer use, the SN770 is the faster drive for sequential operations while the 980 offers marginally more consistent latency under extreme workloads. At similar pricing, the SN770 is the stronger pick for gaming and general desktop use; the 980 is preferable if the system will run sustained server-style mixed I/O.