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The Toshiba XG6 is a 2018 OEM NVMe SSD built around 96-layer TLC BiCS FLASH and an SLC write cache. Its 1TB model is rated for sequential reads up to 3,180 MB/s and writes up to 2,960 MB/s, but those are manufacturer peak figures—not a promise of sustained speed for every capacity or workload. In Tom’s Hardware’s 2018 test, write speed fell to about 1.6 GB/s after the workload exhausted the cache.
What the Toshiba XG6 is
The XG6 is a single-sided M.2 2280 SSD using PCIe Gen3 x4 and NVMe. KIOXIA’s product brief lists three capacities: 256GB, 512GB, and 1TB. It was designed primarily as an OEM component for computer makers, rather than as a conventional retail upgrade drive. Tom’s Hardware and HotHardware described it as not separately sold at retail at their 2018 review dates; that historical status does not establish current availability.
The headline technology was fourth-generation, 96-layer 3D TLC BiCS FLASH, paired with an SLC cache to handle burst writes. In its July 24, 2018 launch announcement, Toshiba Memory Corporation called the XG6 the first SSD to use 96-layer 3D flash, a company claim scoped to that date. The announcement also claimed 40% more capacity per chip than its prior 64-layer design; that refers to chip density, not the drive’s advertised capacity. KIOXIA XG6 product information and Toshiba Memory’s July 24, 2018 launch announcement describe the platform.
How fast is the XG6 by capacity?
KIOXIA’s 2023 product brief gives different sequential maxima for each capacity. The figures below are manufacturer specifications measured using 128 KiB units under the company’s test conditions. KIOXIA cautions that results vary with host device, workload, and file size.
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![Toshiba XG6 KXG60ZNV512G 512 GB Solid State Drive - M.2 2280 Internal - PCI Express [PCI Express 3.1 x4]](https://m.media-amazon.com/images/I/41F8NAae2RL._SL160_.jpg)
- Sequential Read/Write up to (MB/s): 3100/2800
- MTTF: 1.5 million hours
- Compatibility: All systems that support NVMe PCIe Gen3 x4 M.2 2280 SSD
| Capacity | Sequential read, maximum | Sequential write, maximum | TBW endurance rating |
|---|---|---|---|
| 256GB | 3,050 MB/s | 1,550 MB/s | 150 TBW |
| 512GB | 3,100 MB/s | 2,800 MB/s | 300 TBW |
| 1TB | 3,180 MB/s | 2,960 MB/s | 600 TBW |
These values are listed in KIOXIA’s XG6 product brief. They show why “the XG6 writes at 3 GB/s” is too broad: the 256GB model’s specified maximum is 1,550 MB/s, while the near-3,000 MB/s figure applies to the 1TB model under manufacturer test conditions.
Why write speed can fall during long transfers
The SLC cache lets the drive accept bursts of data quickly. Once a write workload exceeds the available cache, data may be written at the slower native TLC rate. In Tom’s Hardware’s 2018 testing, write performance dropped to roughly 1.6 GB/s after the workload passed the cache; its performance page reports about 1.57 GB/s at an 8 MB file size. Those are observations from that review’s workload, not guaranteed sustained rates for every XG6, host, or transfer.
Rank #2
For ordinary short writes, the cache can help the drive approach its headline figures. For a large, uninterrupted transfer, the post-cache behavior is more relevant. The capacity-specific manufacturer maxima and the review’s test result describe different conditions, so they should not be treated as contradictory measurements of one fixed speed.
Sequential and random performance are different
Sequential throughput describes large, orderly transfers, such as copying a large file. Random I/O measures many small accesses and is commonly expressed as IOPS. For the 1TB XG6, KIOXIA specifies up to 355,000 random read IOPS and 365,000 random write IOPS using 4 KiB units under its test conditions. These peak specifications do not directly predict performance in every application; the host and workload affect results.
Rank #3
- Broad Compatibility: Works with Steam Deck, ROG Ally, Microsoft Surface, and select Dell laptops for easy portable upgrades
- PCIe 4.0 Performance: Delivers up to 7,100MB/s read and 6,000MB/s write speeds for quicker game load times, bootups, and smooth multitasking
- Spacious NVMe SSD: This 1TB SSD provides space for AAA games, apps, and media with compact M.2 2230 NVMe SSD form factor for casual gamers and home users
- Power-efficient Design: Engineered for low power draw to extend battery life on handheld consoles and laptops
- Trusted Micron Quality: Built with advanced G8 NAND and thermal control for reliable Gen4 performance trusted by gamers and home users
Power, security, and endurance specifications
KIOXIA lists active-power maxima and L1.2 low-power consumption by capacity. These are manufacturer specifications, not independent battery-life measurements.
| Capacity | Active power, maximum | L1.2 low-power mode | TBW |
|---|---|---|---|
| 256GB | 4.0 W | 3.0 mW | 150 |
| 512GB | 4.1 W | 3.0 mW | 300 |
| 1TB | 4.7 W | 3.0 mW | 600 |
The product brief lists optional TCG Opal 2.01 self-encrypting-drive models. Confirm the exact model and system support if hardware encryption matters. TBW is the manufacturer’s endurance rating, not evidence of an observed failure rate; the cited sources do not establish long-term reliability outcomes.
Rank #4
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- 【HIGH-SPEED TRANSMISSION】Accelerate the reading and writing performance of solid-state hard drives through intelligent SLC cache technology, up to 3000MB/s read speed and 1300MB/s write speed, greatly improving the speed of booting, program opening, game loading, file saving and transmission, etc
- 【PREFERRED CHIP】fanxiang S501Q ssd NVMe uses 3D NAND technology and high-quality particles, which further improves product life and stability. There is no internal mechanical mechanism, good shock resistance, and high data security
- 【WIDELY COMPATIBLE】Internal SSD is compatible with Windows 8, 10, 11, Mac OS10.9, and later. Compatible with laptops, desktops, and all-in-one computers (computer motherboard must be equipped with M.2 interface)
- 【LONG SERVICE】fanxiang is committed to providing high-quality products to global business partners, providing a 3-year service (installation screws and screwdrivers are included in the product package)
Compatibility and warranty matter for an OEM drive
A matching M.2 2280 shape is not enough to guarantee that an XG6 will work in a particular computer. The host must support an M.2 NVMe drive over PCIe, and physical clearance, firmware support, and system-specific configurations can also matter. Check the computer maker’s documentation for the exact system before buying or installing a replacement.
Tom’s Hardware reported a five-year warranty in its review table but noted that OEMs have latitude in how warranty coverage is passed through. A used or pulled OEM drive may not carry the same coverage as a drive installed in its original computer. Check the seller’s terms and, where applicable, the computer maker’s warranty conditions.
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- ?Model?KBG40ZNS256G
- ?Digital Storage Capacity?256GB
- ?Hardware Interface?PCI Express
- ?Form Factor?M.2 2230
- ?OEM?The SSD was pulled from BRAND NEW laptops for upgrade purpose. The SSD has been wiped and formatted. OEM packaging
Verdict: a fast OEM SSD, with a cache-dependent ceiling
The XG6 was a notable early 96-layer TLC NVMe design. Its 1TB specification reaches 3GB/s-class sequential reads and writes, while the smaller models—especially the 256GB version—have lower write maxima. Long writes can slow after the SLC cache fills, as Tom’s Hardware observed in its 2018 workload. It is best understood as a capable component from its era, not as a universally available retail drive or a guarantee of sustained 3GB/s transfers.
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