Fanxiang S770 4TB Review — High-Capacity PCIe 4.0 with Questions (2026)
Quick answer
The Fanxiang S770 4 TB is a drive for buyers who prioritise raw gigabytes-per-dollar above all else and have a backup strategy they trust.
Read: 7300 MB/s Write: 6800 MB/s Endurance: 2800 TBW Warranty: 5 years Interface: M.2 4.0 x 4
The Fanxiang S770 at 4 TB is the highest-stakes version of this drive — you are paying for capacity and speed, but the component lottery that haunts the smaller capacities gets harder to ignore when the price tag climbs.
Controller & Memory
The 4 TB S770 is built around the same InnoGrit IG5236 controller and DDR4 DRAM cache as the rest of the lineup, but the NAND configuration at this density is the least predictable part of the package. While the 1 TB and 2 TB models typically ship with YMTC 128-layer TLC, forum reports suggest 4 TB units have appeared with Micron 176-layer NAND — and some buyers actively prefer that, since YMTC 128L flash has a documented history of corruption complaints in enthusiast communities. Fanxiang does not disclose which NAND is in any given unit, so you are buying blind.
The drive is a double-sided M.2 2280 design with a heatsink included in the box. Capacities in the S770 family run from 1 TB up to this 4 TB flagship, with the 2 TB model generally regarded as the sweet spot for performance-per-dollar. At 4 TB, the value equation shifts: you are now spending enough that a single-component failure represents a meaningful financial loss, and Fanxiang's support track record does not inspire confidence for high-value claims.
Direct competitors at 4 TB include the Silicon Power US75, Lexar NM790, and Team Group MP44 — all PCIe 4.0 drives with DRAM caches and established RMA pipelines. The S770 4 TB typically undercuts them on price, but the gap is narrower at this capacity tier and the risk-reward calculus tilts toward known quantities.
Storage Comparisons:
S770 Performance & Benchmarks
Rated performance is 7,300 MB/s sequential reads and 6,800 MB/s sequential writes, matching the 2 TB variant. Random IOPS are in the 860,000 read and 675,000 write range. The IG5236's pseudo-SLC cache should scale with capacity, giving the 4 TB model a generous write-cache buffer — likely over 1 TB before exhausting to native TLC speed — which makes it the most capable S770 for sustained large-file transfers and the best choice for users who regularly move multi-hundred-gigabyte data sets.
Fanxiang S770 4 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.
- Patriot Viper PV593 1 TB: 14,500 MB/s read, 14,000 MB/s write
- Patriot Viper PV593 2 TB: 14,500 MB/s read, 14,000 MB/s write
- Patriot Viper PV593 4 TB: 14,500 MB/s read, 14,000 MB/s write
- Patriot Viper PV573 2 TB: 14,000 MB/s read, 12,000 MB/s write
- Fanxiang S770 4 TB (this drive): 7,300 MB/s read, 6,800 MB/s write
However, UserBenchmark aggregate data paints a less flattering picture: across 264 user-submitted samples, the S770 4 TB shows up to 376% score variance, classified as terrible consistency. This likely reflects the mixed-hardware-revision problem — different NAND batches performing differently under the same model name — rather than a single design flaw. For a gaming or media library drive, this inconsistency is unlikely to matter because reads dominate and writes are bursty. For a scratch disk or write-intensive application, unpredictable performance is a genuine liability that makes the drive hard to recommend.
Fanxiang S770 vs Competitors
See how the S770 stacks up against other M.2 4.0 x 4 drives in our database:
Compare with rival drives:
Endurance, TBW & Warranty
The S770 4 TB carries a 5-year warranty, and while Fanxiang does not publish an official TBW figure for this capacity, the 2 TB model's 1,400 TBW scales to an estimated 2,800 TBW at 4 TB. That is ample for any consumer workload — at 50 GB per day it translates to over 150 years of writes. The practical warranty limitation is Fanxiang's customer support infrastructure: multiple user reports describe ignored RMA requests, and some buyers have only obtained refunds after escalating through Amazon or their payment provider. A 5-year warranty from a company that does not answer emails is not worth much.
Fanxiang S770 4 TB Specifications
| Category | Value |
|---|---|
| Capacity [?] | 4 TB |
| Interface [?] | M.2 4.0 x 4 |
| Controller [?] | Innogrit IG5236 |
| Memory type [?] | YMTC 128-l TLC |
| DRAM [?] | Yes |
| Read speed (MB/s) [?] | 7300 |
| Write speed (MB/s) [?] | 6800 |
| Read IOPS [?] | 860000 |
| Write IOPS [?] | 675000 |
| Endurance (TBW) [?] | 2800 |
| MTBF (million hours) [?] | 2000000 |
| Warranty (years) [?] | 5 |
Verdict: Is the S770 Worth It in 2026?
The Fanxiang S770 4 TB is a drive for buyers who prioritise raw gigabytes-per-dollar above all else and have a backup strategy they trust. It works as a game library repository, a media drive, or bulk storage where the data is replaceable. It is a poor choice as a primary boot drive, a workstation scratch disk, or any role where a sudden failure would cost you real money or lost work. At the 4 TB price point, the step up to a Lexar NM790 or Silicon Power US75 buys you comparable performance from companies that actually answer warranty emails.
+ Pros
- 7,300 MB/s reads and 6,800 MB/s writes on PCIe 4.0
- DDR4 DRAM cache at all capacities
- Massive 4 TB of storage with generous SLC cache buffer
- Includes heatsink and mounting hardware
- Aggressively priced against brand-name 4 TB PCIe 4.0 drives
- Cons
- NAND vendor varies by production batch with no disclosure
- UserBenchmark shows extreme performance variance across samples
- Warranty support is practically unreachable per widespread user reports
- Double-sided PCB limits laptop and PS5 compatibility
- At 4 TB the financial risk of an unsupported failure is not trivial
Buy this or similar SSD Storage:
Video Review
Fanxiang S770 4TB SSD for PS5 – Insane Speed & Storage You Didn’t Know You Needed!
