Kioxia BG4 1TB - M.2 2230 PCIe 3.0 NVMe SSD

Posted on May 17, 2026 by Raymond Chen

The Kioxia BG4 1TB is a tiny single-package M.2 2230 NVMe used heavily by laptop OEMs and as a popular Steam Deck and ROG Ally upgrade target - 2,300 MB/s reads from a 96-layer BiCS4 TLC HMB design.

Kioxia BG4 1TB - M.2 2230 PCIe 3.0 NVMe SSD

The Kioxia BG4 1 TB (KBG40ZNS1T02) packs an in-house Kioxia eight-channel NVMe controller, 96-layer BiCS4 3D TLC NAND, and the host system's Host Memory Buffer (HMB) capability onto a single M.2 2230 module measuring 22 by 30 millimetres. It is the OEM successor to the BG3 (PCIe 3.0 x2) and uses the full PCIe 3.0 x4 interface for materially higher peak speeds. The compact 2230 form factor is the drive's main selling point: it slots cleanly into space-constrained devices including the Steam Deck, Steam Deck OLED, ASUS ROG Ally, Lenovo Legion Go, several Microsoft Surface variants, and the M.2 2230 slot on numerous business and ultrabook laptops.

Kioxia ships the BG4 in 128 GB, 256 GB, 512 GB, and 1 TB capacities, plus a surface-mount M.2 1620 BGA package for direct-to-board OEM integration. The 1 TB you see here is the highest-capacity removable BG4 module and currently the standard upgrade target for handhelds because the factory configurations ship at 256 GB or 512 GB. The product is officially an OEM-only design, so it is sold via system integrators, second-source distributors such as drivesolutions.com, and surplus channels on Amazon and eBay rather than through Kioxia's retail line.

Direct rivals at the M.2 2230 form factor are the WD Black SN770M 1 TB (PCIe 4.0, faster but warmer), the Sabrent Rocket 2230 (PCIe 4.0), the Corsair MP600 Mini 1 TB (PCIe 4.0), and the Kioxia BG5 1 TB (the BG4's PCIe 4.0 successor). Within those, the BG4 sits at the conservative end of the field - PCIe 3.0 only, no on-board DRAM - which trades raw speed for the lowest power consumption of any 1 TB 2230 drive on the market.

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🚀 Performance and benchmarks

Manufacturer ratings for the BG4 1 TB land at 2,300 MB/s sequential reads and 1,800 MB/s sequential writes, with random performance up to 390,000 read and 200,000 write IOPS at high queue depths. Reviewers at KitGuru, StorageReview, and The SSD Review consistently measured CrystalDiskMark sequential reads within a few percent of the rating, with strong random-read performance for an HMB design - the BG4's read IOPS is unusually high for a DRAM-less drive of its era.

Performance comparison

Kioxia BG4 1 TB vs M.2 3.0 x 4 2230 S3 peers

Switch between sequential throughput and random IOPS to see how this drive stacks up against other M.2 3.0 x 4 2230 S3 SSDs in our database. The highlighted bar is the drive on this page — click any other bar to open that drive.

Kioxia BG4 1 TB (this drive): 2,300 MB/s read, 1,800 MB/s write
Kioxia BG4 128 GB: 2,300 MB/s read, 1,800 MB/s write
Kioxia BG4 256 GB: 2,300 MB/s read, 1,800 MB/s write
Kioxia BG4 512 GB: 2,300 MB/s read, 1,800 MB/s write

Sustained writes show the limitation: with no on-board DRAM and the dense BGA package limiting thermal dissipation, the BG4 falls into TLC direct-write rates fairly quickly under continuous load. Reviewers observed write performance dropping below 800 MB/s after the SLC cache exhausts on a near-full drive. For a handheld upgrade or laptop boot drive that profile is invisible - game level loads, application launches, and OS responsiveness all benefit from the high random-read rating. For sustained capture or large dataset moves, plan around the limit. Active power consumption peaks around 3.7 W (typical), which is one of the BG4's strengths in handheld devices: it consumes less power than the WD Black SN770M and stays cooler in the Steam Deck's tight thermal envelope.

🖥️ Endurance and warranty

Because the BG4 is an OEM-only product, warranty length depends on the channel through which the drive was purchased. Devices shipped from a system integrator (Dell, HP, Lenovo, Microsoft Surface, Valve, ASUS) carry the host-device warranty, typically one to two years. Drives bought as bare modules through second-source resellers may carry a shorter limited warranty (often one year) or no warranty at all - check the seller's listing carefully before purchase. Kioxia itself does not publish a consumer TBW figure for the BG4 in its public product brief, and there is no direct-to-Kioxia consumer RMA channel for an OEM module. For mission-critical use, plan a backup target and treat the BG4 as a reliable but unwarranted upgrade rather than a serviceable consumer drive. The published MTBF rating is 1.5 million hours.

📊 Specs

Category	Value
Capacity [?]	1 TB
Interface [?]	M.2 3.0 x 4 2230 S3
Controller [?]	Toshiba
Memory type [?]	Kioxia 96-L TLC
DRAM [?]	HMB
Read speed (MB/s) [?]	2300
Write speed (MB/s) [?]	1800
Read IOPS [?]	390000
Write IOPS [?]	200000
Endurance (TBW) [?]	n/a
MTBF (million hours) [?]	1.5
Warranty (years) [?]	5

Conclusion

The Kioxia BG4 1 TB is the conservative pick for an M.2 2230 upgrade in handhelds and ultrabooks where battery life and thermal headroom matter more than peak throughput. Steam Deck, ROG Ally, and Legion Go owners who want longer runtime should consider the BG4 over the WD Black SN770M 1 TB or Corsair MP600 Mini 1 TB, both of which are faster but warmer and more power-hungry. Skip the BG4 if your priority is peak performance for a desktop-class workload, or if you need a stronger warranty channel - in either case, the Kioxia BG5 1 TB (PCIe 4.0, same form factor) or WD Black SN770M 1 TB are better fits. As a low-power, low-heat, mid-speed 2230 NVMe, the BG4 1 TB remains one of the cleanest handheld upgrades on the market.

+ Pros

2,300 MB/s reads in M.2 2230 form factor
390,000 IOPS rated random reads
Low 3.7 W typical power for handheld battery life
Stays cool in Steam Deck and ROG Ally thermal envelopes
Kioxia in-house 96-layer BiCS4 TLC NAND
Single-package design eases handheld installation

- Cons

PCIe 3.0 only, slower than BG5 successor and SN770M
DRAM-less HMB design lags on heavy random writes
OEM-only distribution complicates retail warranty
No published TBW endurance rating from Kioxia
Sustained writes drop below 800 MB/s after SLC cache

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⁉️ FAQ

Yes, it is one of the most popular Steam Deck upgrades. The BG4 1 TB fits the Steam Deck's M.2 2230 slot directly without an adapter and consumes notably less power than PCIe 4.0 alternatives such as the WD Black SN770M 1 TB or Corsair MP600 Mini 1 TB - meaningful for handheld battery life. The Steam Deck's PCIe 3.0 x4 interface matches the BG4's bandwidth exactly, so there is no headroom lost by stepping down from PCIe 4.0. Real-world game load times on SteamOS are within a few seconds of any other M.2 2230 drive, since the Deck is GPU-bound rather than storage-bound in most titles.

Yes, both handhelds accept M.2 2230 modules and the BG4 1 TB drops in without an adapter. The ROG Ally and Legion Go each ship with a 512 GB 2230 NVMe as standard; upgrading to the BG4 1 TB doubles capacity without changing the form factor. The Legion Go's PCIe 4.0 interface means the BG4 will run at PCIe 3.0 speeds rather than the slot's full bandwidth, so if peak throughput matters use a PCIe 4.0 drive like the WD Black SN770M instead. If battery life and thermals matter more, the BG4 is the safer pick.

No, the BG4 is a DRAM-less design that uses Host Memory Buffer (HMB) instead. HMB borrows a small slice of system RAM, typically less than 100 MB, to hold the logical-to-physical mapping table that a dedicated DRAM cache would otherwise hold. The trade-off is cost, thermals, and PCB area: Kioxia uses the savings to fit the BG4 into the single-package 2230 form factor where dedicated DRAM would not physically fit. The practical penalty is modest on modern Windows or SteamOS platforms for read-heavy workloads, but heavier on sustained random writes.

Kioxia does not publish a TBW figure for the consumer-equivalent BG4 1 TB module. The product is OEM-only, and Kioxia's public product brief lists only the typical performance and power figures rather than an endurance rating. Internal endurance for BG4 is likely in the 200-300 TBW range based on comparable 96-layer BiCS4 TLC OEM drives, but that is an estimate rather than a published figure. For mission-critical capture or video workloads, choose a consumer drive with a published TBW; for handheld gaming and laptop boot use, the BG4's endurance will exceed realistic write volume by a wide margin.

The BG5 is the PCIe 4.0 successor and the natural next step. Sequential reads roughly double to 3,500-5,000 MB/s depending on capacity, random reads climb to around 700,000 IOPS, and the controller adds modest power management improvements while staying inside the same 2230 form factor. Power draw remains low for a PCIe 4.0 drive, though slightly higher than the BG4. For new upgrades on a PCIe 4.0 host (ROG Ally, Legion Go, current laptops), the BG5 is the better choice; for PCIe 3.0 hosts (Steam Deck LCD, older laptops) the BG4 captures the full host bandwidth and consumes less power.

Only for the M.2 2230 slot - on a standard 2280 slot, choose a current PCIe 4.0 NVMe. For handheld and ultrabook 2230 upgrades, the BG4 1 TB remains relevant where its low power consumption and conservative thermals matter more than peak speed. It is also typically cheaper than PCIe 4.0 2230 alternatives such as the WD Black SN770M 1 TB or Corsair MP600 Mini 1 TB, which makes it the value pick for a Steam Deck capacity bump. For new ROG Ally or Legion Go upgrades targeting peak speed, the Kioxia BG5 1 TB is the better technical successor.

Only with an M.2 2230-to-2280 adapter bracket. The BG4 is physically 30 mm long; a standard M.2 2280 slot expects 80 mm. Adapters are cheap and widely available but introduce a small thermal disadvantage because the longer board area normally helps spread heat. There is no electrical reason the BG4 cannot work in a 2280 desktop slot - it is a standard PCIe 3.0 x4 NVMe device - but the drive is overspecified for power efficiency and underspecified for peak speed in a desktop scenario. For desktop builds, choose a 2280 PCIe 4.0 drive such as the WD Black SN770 1 TB or Crucial P3 Plus 1 TB instead.