# Kioxia BG4 128GB Review — Ultra-Compact OEM NVMe SSD (2026)

The Kioxia BG4 128GB is an ultra-compact OEM NVMe SSD built for thin laptops and ultrabooks — a single-chip M.2 2230 drive with 3D TLC NAND and HMB support that prioritizes efficiency over peak performance.

Quick answer: The Kioxia BG4 128GB is a competent OEM boot drive — its ultra-compact 2230 form factor fits where no other NVMe drive can, the 2,300 MB/s reads are respectable for PCIe 3.0, and the 3D TLC NAND offers better endurance than QLC alternatives. But 128 GB is very limiting for modern use, the DRAM-less design caps random I/O performance, and the OEM-only nature means warranty support is inconsistent. If you're upgrading a laptop that uses the BG4, the 512 GB or 1 TB variants are significantly more practical. For DIY builders, retail drives like the WD Blue SN580 offer better performance, documented specs, and direct warranty support at similar prices.

## Specifications

| Specification | Value |
| --- | --- |
| Capacity | 128 GB |
| Interface | M.2 3.0 x 4 2230 S3 |
| Controller | Toshiba |
| Memory type | Toshiba 3D TLC |
| DRAM cache | HMB |
| Sequential read | 2300 MB/s |
| Sequential write | 1800 MB/s |
| Random read IOPS | 390000 |
| Random write IOPS | 200000 |
| Endurance | 120 TBW |
| MTBF | 1.5 |
| Warranty | 5 years |

## Performance

The Kioxia BG4 128GB is rated at up to 2,300 MB/s sequential reads and 1,800 MB/s sequential writes over its PCIe 3.0 x4 NVMe interface. The read speed is solid for a PCIe 3.0 drive — about 58% of the interface's theoretical 4,000 MB/s ceiling. The write speed of 1,800 MB/s reflects the 128 GB capacity's limited NAND die count; larger BG4 variants reach higher write speeds because the controller can address more dies in parallel. The BG4 uses a DRAM-less design with HMB (host memory buffer), which means random 4K performance is modest — typically in the 30,000–50,000 IOPS range for reads and 20,000–40,000 IOPS for writes. This is adequate for boot drive duties — OS loading, application launches, and web browsing — but noticeably lower than DRAM-equipped NVMe drives that reach 200,000+ IOPS. The single-chip design is power-efficient, which matters most in the ultrabooks and tablets where this drive is typically found. Tom's Hardware's review of the BG4 praised its power efficiency and noted 'speedy application performance' despite the DRAM-less design. The sustained write performance was rated as 'decent' — the 3D TLC NAND maintains reasonable speeds after the SLC cache fills, unlike QLC drives that drop dramatically. For a 128 GB OEM boot drive, the BG4's performance is well-matched to its intended role in thin laptops and ultrabooks. It's not a gaming or content-creation drive, but for everyday computing in a compact system, it delivers responsive performance with minimal power draw.

## Endurance, TBW & Warranty

The Kioxia BG4 is an OEM-only drive, which means warranty terms depend on the original equipment manufacturer rather than Kioxia directly. The DB lists a 5-year warranty, which aligns with Kioxia's standard warranty for the BG4 series in OEM contracts. However, end-user warranty coverage varies — if you purchased a laptop with the BG4 pre-installed, your laptop manufacturer's warranty applies. If you sourced the drive separately from the secondary market, warranty coverage may be limited or nonexistent. Kioxia does not publish a TBW (terabytes written) endurance rating for the BG4 in its public documentation. For a 128 GB drive using 3D TLC NAND, endurance is likely in the 70–120 TBW range based on comparable OEM drives. At a typical 15–30 GB per day write workload in a laptop environment, the drive should last 6–22 years before reaching its estimated TBW limit. The 3D TLC NAND provides better endurance than QLC alternatives commonly found in OEM drives at this price point. An MTBF figure is not publicly published for the BG4. For buyers sourcing this drive through OEM channels or the secondary market, the lack of direct-to-consumer warranty support is a consideration — you're relying on the drive's inherent durability and the original system manufacturer's coverage rather than a standalone warranty.

## Pros and Cons

**Pros:**

- Ultra-compact M.2 2230 form factor
- 2,300 MB/s reads for PCIe 3.0
- 3D TLC NAND better than QLC alternatives
- Power-efficient single-chip design
- HMB support for DRAM-less efficiency
**Cons:**

- Only 128 GB capacity
- DRAM-less limits random I/O performance
- OEM-only — no direct retail warranty
- 128 GB variant has lowest write speeds
- Not available through normal retail channels


## Verdict

The Kioxia BG4 128GB is a competent OEM boot drive — its ultra-compact 2230 form factor fits where no other NVMe drive can, the 2,300 MB/s reads are respectable for PCIe 3.0, and the 3D TLC NAND offers better endurance than QLC alternatives. But 128 GB is very limiting for modern use, the DRAM-less design caps random I/O performance, and the OEM-only nature means warranty support is inconsistent. If you're upgrading a laptop that uses the BG4, the 512 GB or 1 TB variants are significantly more practical. For DIY builders, retail drives like the WD Blue SN580 offer better performance, documented specs, and direct warranty support at similar prices.

## Frequently Asked Questions

### What devices use the Kioxia BG4 128GB?

The BG4 is an OEM-only drive found in pre-built laptops and tablets. It's commonly used in Microsoft Surface devices, Lenovo ThinkPad ultrabooks, and other compact systems that require the M.2 2230 form factor. The 2230 size (22mm x 30mm) is much smaller than the standard 2280 M.2, fitting in devices where internal space is at an absolute premium. You won't find the BG4 sold retail through normal consumer channels — it's sourced through OEM distributors.

### Does the Kioxia BG4 128GB have DRAM?

No, the BG4 is a DRAM-less drive that uses HMB (host memory buffer) instead. HMB borrows a small amount of system RAM (typically 64–128 MB) to store the flash translation layer map, eliminating the need for dedicated on-drive DRAM. This saves cost, power, and space — all critical in the ultrabooks and tablets where the BG4 is installed. The trade-off is lower random I/O performance compared to DRAM-equipped drives, but for boot drive duties the difference is acceptable.

### Can I upgrade my laptop's Kioxia BG4 to a larger capacity?

If your laptop uses an M.2 2230 slot, you can upgrade to a larger BG4 variant (256 GB, 512 GB, or 1 TB) or any other M.2 2230 NVMe SSD. The larger BG4 capacities offer better write speeds because they have more NAND dies for the controller to address. However, many devices that use the BG4 — like Microsoft Surface tablets — have soldered or adhesively-mounted SSDs that are difficult or impossible to replace. Check your device's service manual before attempting an upgrade. Some devices use proprietary connectors that only fit specific OEM drives.

### What is the TBW endurance of the Kioxia BG4 128GB?

Kioxia does not publish an official TBW rating for the BG4 in its public documentation. For a 128 GB drive using 3D TLC NAND, endurance is likely in the 70–120 TBW range based on comparable OEM drives. At 15–30 GB of writes per day in a typical laptop environment, the drive should last 6–22 years before reaching its estimated TBW limit. The 3D TLC NAND provides better endurance than QLC alternatives. Since the BG4 is an OEM drive, endurance guarantees depend on the original equipment manufacturer's warranty terms.

### Is the Kioxia BG4 128GB good for gaming?

No, 128 GB is far too small for a modern gaming drive. After Windows (20–30 GB), you'll have roughly 80–90 GB available — enough for 1–2 modern AAA titles. The BG4 is designed as a boot drive for thin laptops and ultrabooks, not as a gaming storage solution. The DRAM-less design also means sustained game loading performance is lower than on DRAM-equipped drives. For gaming, a retail 500 GB or 1 TB NVMe like the Crucial P3 Plus or WD Blue SN580 is a much better choice.

### How does the BG4 compare to the WD SN520 128GB?

Both are OEM-only M.2 2230 NVMe SSDs designed for ultrabooks and compact devices. The BG4 has higher rated sequential speeds — 2,300 MB/s reads and 1,800 MB/s writes versus the SN520's roughly 1,700/850 MB/s. Both are DRAM-less with HMB. The BG4 uses 3D TLC NAND while the SN520 also uses TLC. The BG4's single-chip design is more power-efficient. Both are not available through retail channels. The BG4 generally offers better performance, while the SN520 is found in a wider range of OEM devices.

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Last updated: 2026-05-23. Source: https://ssdrive.net/kioxia-bg4-128-gb