# Fanxiang S770 4TB Review — High-Capacity PCIe 4.0 with Questions (2026)

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.

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. 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.

## Specifications

| Specification | Value |
| --- | --- |
| Capacity | 4 TB |
| Interface | M.2 4.0 x 4 |
| Controller | Innogrit IG5236 |
| Memory type | YMTC 128-l TLC |
| DRAM cache | Yes |
| Sequential read | 7300 MB/s |
| Sequential write | 6800 MB/s |
| Random read IOPS | 860000 |
| Random write IOPS | 675000 |
| Endurance | 2800 TBW |
| MTBF | 2000000 |
| Warranty | 5 years |

## Performance

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.

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.

## 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.

## Pros and Cons

**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


## Verdict

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.

## Frequently Asked Questions

### What kind of NAND does the Fanxiang S770 4TB use?

It depends on the production batch, and Fanxiang does not disclose which NAND is in any given unit. Early S770 models used YMTC 128-layer TLC (Xtacking 2.0), but forum reports indicate 4 TB units have also shipped with Micron 176-layer NAND and possibly SK Hynix flash. There is no way to know which you will receive without installing the drive and running a flash ID utility. Some buyers prefer the Micron-sourced units since YMTC 128L has been linked to data corruption reports in enthusiast communities.

### Is the Fanxiang S770 4TB good for gaming?

As a pure game library drive, yes — the 7,300 MB/s reads handle DirectStorage and game loads effortlessly, and the 4 TB capacity means you can keep a large library installed without juggling. The concern is reliability: if the drive fails and your game saves are not cloud-synced, you lose progress. For Steam or PlayStation libraries with cloud saves enabled, the risk is mainly the inconvenience of re-downloading.

### Does the Fanxiang S770 4TB work in the PS5?

The S770 meets Sony's PCIe 4.0 x4 and 5,500 MB/s read requirements, and users have reported successful PS5 operation. The double-sided PCB and included heatsink add thickness — verify the total assembly height against the PS5's 11.25 mm slot limit before closing the expansion bay cover. If the fit is too tight, a lower-profile aftermarket heatsink may be necessary.

### What is the TBW endurance of the Fanxiang S770 4TB?

Fanxiang does not publish an official TBW for the 4 TB model. Based on the 2 TB variant's 1,400 TBW rating, the 4 TB endurance should scale to roughly 2,800 TBW. At a daily write load of 50 GB, that works out to over 150 years — the NAND will almost certainly outlive the drive's practical useful life under normal consumer workloads.

### How does the Fanxiang S770 4TB compare to the Lexar NM790 4TB?

Both are PCIe 4.0 drives with DRAM caches and 7,000+ MB/s read ratings. The NM790 uses a Maxio MAP1602 controller paired with YMTC or Longsys NAND depending on the batch — but Lexar, as a brand under the Longsys umbrella, has more consistent sourcing and a functioning global warranty process. The S770 typically undercuts the NM790 on price, but at 4 TB the savings may not justify the support gap for most buyers.

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Last updated: 2026-08-10. Source: https://ssdrive.net/fanxiang-s770-4-tb