# UNIS SSD S5 Ultra 4TB Review — DRAM, Speed and 2,000 TBW (2026)

The UNIS S5 Ultra 4TB tops the line with a 4 GB DRAM cache, 14,200 MB/s PCIe 5.0 reads and a 2,000 TBW endurance budget for heavy creative work.

Quick answer: The UNIS S5 Ultra 4TB suits workstation builders and archivists who want 4TB of DRAM-cached TLC at full PCIe 5.0 ratings and are willing to import from a Tsinghua-backed brand with minimal Western retail presence: 4 GB of DRAM, 2,000 TBW endurance and a 5-year warranty are genuinely competitive specifications. Skip it if after-sales service and easy returns are priorities — the Crucial T705 4TB and Samsung 9100 Pro 4TB rate faster sequentially, buy through ordinary channels, and carry deeper review track records. As a statement of how far Chinese storage brands have closed the specification gap, the Ultra is convincing; as a friction-free purchase, it is not quite there yet.

## Specifications

| Specification | Value |
| --- | --- |
| Capacity | 4 TB |
| Interface | M.2 5.0 x 4 |
| Controller | Maxio MAP1602 |
| Memory type | 3D TLC |
| DRAM cache | Yes |
| Sequential read | 14200 MB/s |
| Sequential write | 13400 MB/s |
| Random read IOPS | 1700000 |
| Random write IOPS | 1600000 |
| Endurance | 2000 TBW |
| MTBF |  |
| Warranty | 5 years |

## Performance

UNIS rates the S5 Ultra 4TB at 14,200 MB/s sequential reads, 13,400 MB/s writes and up to 1,700K random-read and 1,600K random-write IOPS — the only capacity in the line whose random ratings the launch coverage published explicitly. The 4 GB DRAM cache underpins those random numbers, keeping 4TB of mapping tables in dedicated memory rather than trading HMB bandwidth with the operating system. These remain first-party figures: Tom's Hardware noted at launch that only independent testing can confirm them, and published reviews are still rare.

At rated speed the use cases are unambiguous. Four terabytes of 8K footage, a local language model or a full game library sits behind a link that moves 100 GB in about eight seconds, and random performance strong enough for 1,700K reads keeps scratch disks and virtual machine fleets responsive. Sustained writes still settle to native TLC rates once the pseudo-SLC cache fills, standard for the class, though the external DRAM typically keeps post-cache behavior more even than DRAM-less Gen5 designs manage. Thermals are engineered rather than hoped for: UNIS specifies firmware control under 78 °C loaded and 40 °C idle, with the included graphene pad as first-line cooling. A motherboard heatsink remains worthwhile for marathon transfers.

## Endurance, TBW & Warranty

UNIS's official product page rates the 4TB S5 Ultra at 2,000 TBW endurance with a 5-year warranty, whichever comes first — equivalent to about 1.1 TB of writes per day across the term, far beyond desktop workloads. One discrepancy is worth recording: Chinese launch coverage from GeekPark and Wccftech quoted 2,400 TBW for this capacity, consistent with a 600 TBW-per-terabyte formula, while UNIS's own page lists 2,000 TBW; the official figure is used here and the spec table matches it. The 2TB model rates 1,200 TBW on the same terms. For import buyers the warranty path is the real constraint — claims would likely route through the original seller rather than a local service center, so terms deserve a check before purchase.

## Pros and Cons

**Pros:**

- 14,200 MB/s reads and 13,400 MB/s writes
- 4 GB dedicated DRAM cache
- 2,000 TBW endurance with 5-year warranty
- 1,700K random-read IOPS rating
- Firmware thermal control rated below 78 °C loaded
- 3D TLC NAND, double-sided 2280
**Cons:**

- Minimal retail availability outside China
- Controller never officially named
- Launch coverage quoted 2,400 TBW vs the official 2,000
- No independent benchmark data yet
- Double-sided PCB blocks some laptop slots


## Verdict

The UNIS S5 Ultra 4TB suits workstation builders and archivists who want 4TB of DRAM-cached TLC at full PCIe 5.0 ratings and are willing to import from a Tsinghua-backed brand with minimal Western retail presence: 4 GB of DRAM, 2,000 TBW endurance and a 5-year warranty are genuinely competitive specifications. Skip it if after-sales service and easy returns are priorities — the Crucial T705 4TB and Samsung 9100 Pro 4TB rate faster sequentially, buy through ordinary channels, and carry deeper review track records. As a statement of how far Chinese storage brands have closed the specification gap, the Ultra is convincing; as a friction-free purchase, it is not quite there yet.

## Frequently Asked Questions

### Is the UNIS S5 Ultra 4TB compatible with the PS5?

Electrically and speed-wise it passes Sony's guidance: PCIe 5.0 x4 drives run in the PS5's PCIe 4.0 slot, and the 14,200 MB/s rated read far exceeds the 5,500 MB/s Sony recommends, while 4 TB is generous console storage. The obstacles are mechanical and procedural. The drive is double-sided, which complicates heatsink installation, the included 1 mm graphene pad is thinner than the cooling Sony requires, and the model appears on no official compatibility list. With a third-party PS5 heatsink and clearance checked, it should work — but PS5-specific drives with tested coolers remove the guesswork.

### Does the UNIS S5 Ultra 4TB have a DRAM cache?

Yes — the 4TB model carries 4 GB of dedicated DRAM, double the 2TB variant's 2 GB, per GeekPark's and Sina Finance's launch coverage and Tom's Hardware's report. That extra DRAM is most valuable at this capacity, where the flash translation tables are largest; DRAM-less designs must push those tables through Host Memory Buffer exactly when a 4TB drive is fullest. The external cache is what supports the rated 1,700K random-read and 1,600K random-write IOPS. The base UNIS S5, by contrast, is DRAM-less entirely — the Ultra line exists to offer the DRAM-cached alternative.

### What is the TBW endurance of the UNIS S5 Ultra 4TB?

UNIS's official product page rates the 4TB model at 2,000 TBW with a 5-year warranty, whichever comes first — roughly 1.1 TB of writes per day across the full term, well beyond any desktop workload. Be aware of a source conflict: GeekPark and Wccftech launch coverage quoted 2,400 TBW for this capacity, following a 600 TBW-per-TB formula, but UNIS's own page lists 2,000 TBW, and the official figure governs here. The 2TB model rates 1,200 TBW. At a typical 20 GB of daily writes the budget would last centuries, so the 5-year term is the practical limit; claims route through UNIS or the original seller.

### UNIS S5 Ultra 4TB or Samsung 9100 Pro 4TB?

The Samsung 9100 Pro 4TB rates higher at 14,800/13,400 MB/s on Samsung's in-house Presto controller with 236-layer V-NAND, and it buys through normal retail with Samsung's global warranty and firmware support behind it. The UNIS S5 Ultra 4TB counters with the same 5-year warranty, 2,000 TBW of endurance, a 4 GB DRAM cache and rated speed only 600 MB/s behind on reads — but reaches Western buyers mainly through import channels, with warranty claims routed to the seller. Choose the Samsung for support, reviews and resale certainty; choose the UNIS if the import path is acceptable and the specification sheet leads the decision.

### Which controller does the UNIS S5 Ultra 4TB use?

UNIS has not disclosed it. Officially the drive uses an unnamed 6 nm controller; independently, both Tom's Hardware ('likely the Silicon Motion SM2508') and PCEVA's analysis reach the same inference from the process node and the performance targets, while noting it is speculation pending UNIS confirmation. The certain facts: a 6 nm PCIe 5.0 x4 design with 4 GB of external DRAM on this model, rated 14,200/13,400 MB/s and 1,700K/1,600K IOPS. That architecture mirrors what SM2508-based drives offer, which is why the identification is widely repeated — but no source has confirmed the part number.

### Is the UNIS S5 Ultra 4TB good for gaming?

Performance-wise it is excellent for gaming; economically it is hard to justify. Modern titles rarely exploit more than Gen4 bandwidth, so the felt difference between this drive and a 7,000 MB/s Gen4 model is small outside DirectStorage games, and 4 TB is more about library size than speed. Where the Ultra shines in a gaming context is as the single drive in a creator-plus-gaming system: the 4 GB DRAM cache keeps a large library, recording software and background tasks smooth simultaneously. Gaming-only buyers get the same experience from cheaper Gen4 drives; this capacity rewards mixed professional workloads.

### How does the 4TB S5 Ultra differ from the 2TB model?

Sequential ratings are identical — 14,200 MB/s reads and 13,400 MB/s writes — and the random ratings are quoted the same at 1,700K/1,600K IOPS. Three things differ. DRAM doubles from 2 GB to 4 GB, which matters for translation-table headroom at full capacity; endurance rises from 1,200 TBW to 2,000 TBW on UNIS's official page; and the physical fit is the same double-sided M.2 2280 design on both. The 2TB is the sensible pick for general desktop and smaller creator builds; the 4TB is for media libraries, local AI model storage and multi-VM workstations that actually fill the space.

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Last updated: 2026-09-09. Source: https://ssdrive.net/unis-s5-ultra-4-tb