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At CES 2024, Micron demonstrated two USB4 external SSD concepts: a passively cooled portable design built around an M.2 drive, and a larger, actively cooled desktop design using an 8TB U.3 SSD. Both used ASMedia’s ASM2464PD USB4-to-NVMe bridge, but the demonstrations did not establish a launch date, price, or final retail specification. Micron’s current public SSD catalog does not list either design as a retail product.
Two approaches to a faster external SSD
Micron’s CES display was about what 40Gbps USB4 could enable for external NVMe storage, not a conventional product launch. The contemporaneous CES report described both units as designs under development and cautioned that they were not guaranteed to reach stores in the forms shown.
Portable prototype: M.2 in a transparent enclosure
The smaller concept had a gumstick-like, transparent enclosure containing a 2TB Micron 3400 OEM M.2 2280 PCIe 4.0 SSD. Its design goal was passive cooling: a larger enclosure could provide more surface area and thermal mass than a very compact shell, potentially allowing the drive to run without a fan. That was an engineering aim, not a verified promise of fanless sustained performance. The CES demonstration did not establish a final internal drive, production enclosure, or thermal test result.
Desktop prototype: U.3 capacity, fan, and external power
The larger design paired the USB4 bridge with an 8TB U.3 SSD, a small cooling fan, and an external power supply. It was laid out to stack with other equipment, not to daisy-chain additional devices. Micron also discussed the possibility that it could supply power to a connected notebook over USB4, but the power-delivery details were not finalized in the demonstration. Additional downstream USB-A or USB-C ports were a possible direction, not a confirmed feature.
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Using one U.3 drive rather than combining several M.2 drives through software RAID could simplify the storage topology and provide a single large volume. Enterprise-oriented U.3 drives may also offer more consistent behavior under some workloads than consumer drives whose fastest write rates depend on an SLC cache. Those are potential advantages, not measured results for Micron’s prototype. U.3 hardware can be costly, an external supply reduces portability, and a fan adds noise and a mechanical failure point. A single drive also does not provide the redundancy of a properly configured RAID array.
How the USB4-to-NVMe design works
Both concepts used ASMedia’s ASM2464PD bridge controller. The data path is:
USB4 host → USB-C cable → ASM2464PD bridge → PCIe 4.0 x4 → NVMe SSD
This is a bridge-based design, not a native USB flash-storage controller. It puts a conventional NVMe SSD behind a controller that translates between USB4 and the drive’s PCIe interface. That lets a manufacturer reuse established M.2 or U.3 SSD technology and pair it with a fast external connection. It can support high capacities and high-performance internal drives, but adds another controller, power draw, and heat. The selected SSD’s controller, NAND, firmware, DRAM, and write cache still influence performance.
Rank #2
- External SSD with USB4 Connection: Leverage the incredibly high bandwidth of USB4 to move large files for tasks like video and photo editing in seconds.
- Lightning-Fast Speeds: Delivers data speeds of up to 4,000MB/sec sequential read and up to 3,500MB/sec sequential write.
- Compatible with USB Type-C: Connect via USB Type-C, Thunderbolt 4 and higher for wide compatibility*. *Performance varies by capacity. Maximum performance requires USB4 or higher connection.
- Compact Form Factor: Small form factor allows you to take the EX400U with you for high-performance storage on the go.
- Simple Plug-and-Play Setup: Easy to use right out of the box with a single connection for power and data on PC or Mac.
The ASM2464PD represented a step up from USB 3.2 Gen 2×2-era bridge designs such as the ASM2364. The older class paired a 20Gbps USB interface with PCIe 3.0 x4 storage; the newer controller supports USB4 up to 40Gbps and PCIe 4.0 x4, with USB Type-C Power Delivery functionality integrated. A rough comparison is:
| Design class | Upstream connection | Storage connection | Typical performance class |
|---|---|---|---|
| ASM2364-era bridge | USB 3.2 Gen 2×2, 20Gbps | PCIe 3.0 x4 | Around 2GB/s |
| ASM2464PD-era bridge | USB4, up to 40Gbps | PCIe 4.0 x4 | About 3.5–3.8GB/s at the high end |
These are broad interface and product-class comparisons, not guaranteed speeds for every drive or workload. USB4 external SSDs do not all use the same internal architecture.
40Gbps is not 5GB/s of file-copy speed
Dividing a 40-gigabit-per-second link rate by eight gives 5GB/s of raw bandwidth. That is not the amount of file data a drive can necessarily deliver: protocol overhead, the bridge, the SSD, the host implementation, cable, and workload all reduce usable throughput. As a market reference, ADATA advertises up to 3,800MB/s read and 3,700MB/s write for its USB4 SE920. That illustrates a plausible high-end sequential performance range for this generation, not a result measured on Micron’s prototypes. See the SE920 specifications.
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Peak sequential benchmark speed is only one part of performance. A short benchmark or brief copy may finish before the drive heats up or exhausts its fast pseudo-SLC write cache. Sustained writes, repeated large transfers, small-file work, and performance after the cache fills can look quite different. The CES demonstrations did not establish those measurements.
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- Rugged and Durable Construction: Built with an aluminum body for heat dissipation and durability. Includes a silicone sleeve for enhanced drop protection and resistance to environmental hazards.
- Plug and Play, No External Power Needed: Bus-powered for easy use without external adapters. Comes with a premium Thunderbolt cable for hassle-free, high-performance connections on the go.
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Cooling and power were central design questions
A USB4 NVMe system has both a bridge controller and an SSD controller working at high speed. The resulting heat and power demand make cooling more consequential than in many everyday 10Gbps portable drives. Prolonged load can warm the NAND and controllers, raise enclosure temperature, and trigger thermal throttling. A drive may begin a transfer quickly and slow later; a consumer SSD may also slow after its write cache fills. Neither a top-line speed nor the presence of a fan alone tells you how a particular product behaves in a long transfer.
| Cooling and power approach | What it can offer | Trade-off |
|---|---|---|
| Passive portable | Quiet, simple, and easier to carry | Has to shed heat without a fan; sustained performance depends on thermal design and workload |
| Fan-cooled portable | Active heat removal in a mobile form | Fan noise, moving parts, and a larger or more complex enclosure |
| Fan-cooled desktop with external power | More room for cooling and power-hungry, high-capacity storage | Less portable, requires an outlet, and may be noisy |
ADATA’s SE920 provides a commercial comparison: its shell extends to activate a built-in microfan, and its documentation lists Windows 10/11, macOS 13 or later, Linux kernel 6 or later, and Android 13 or later. Those are product-specific specifications, not proof of compatibility or cooling performance for Micron’s concepts.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.USB-C alone does not guarantee USB4 speed
A USB-C connector identifies the plug, not the capability of the host port. To get USB4-class performance, the computer, cable, drive, and operating-system support must all work together at the required mode. Connect a USB4 SSD to a slower USB port and it will operate at the slower connection’s capability. Host firmware, power budget, and implementation can also affect stability and speed.
Before buying a high-speed external SSD, check the computer’s exact USB4 or Thunderbolt specification, the advertised link speed, the included cable’s rating, operating-system requirements, and whether the drive is bus-powered or needs an adapter. Confirm the expected fallback speed on older ports. Do not assume every USB4 SSD supports every Thunderbolt host: compatibility depends on the specific drive and computer. For example, ADATA explicitly advertises USB 3.2 and USB 2.0 backward compatibility and Thunderbolt 3/4 support for the SE920; that product-specific claim should not be generalized to all devices.
Rank #4
- Rugged, Environmentally Sealed Housing – A heavy-duty housing stands up to the rigors of daily use, with IP55 protection to keep your data safe from the elements
- Unbelievable USB4 Speed on the Go – With transfer speeds rivaling internal drives – up to 40Gbps via USB4 – the EX400U SURVIVOR handles massive video files, game libraries, and creative workloads with ease
- Plug-and-Play Simplicity – One USB Type-C cable handles both power and data – no drivers, no setup, just powerful storage right out of the box
- Wide-Ranging Compatibility – The EX400U SURVIVOR achieves maximum performance on laptop and desktop hosts with USB4/Thunderbolt 4 ports, with additional support for iOS/iPadOS 13 and later devices with USB Type-C ports and backward compatibility with USB Type-C 3.2 *Performance varies by capacity, Maximum performance requires USB4 or higher connection
- Blazing-Fast NVMe Performance – Enjoy up to 4,000MB/sec read and 3,600MB/sec write speeds to move and edit large files in record time *Performance varies by capacity, Maximum performance requires USB4 or higher connection
Why Micron’s demonstration mattered
The broader shift was from common 10Gbps USB storage, through 20Gbps USB 3.2 Gen 2×2 drives, to 40Gbps USB4 systems capable of putting fast PCIe NVMe storage outside the computer. USB4 can remove an interface bottleneck for large sequential transfers, but it does not erase the differences among host ports, SSDs, cooling solutions, and workloads. The two concepts made that trade-off visible: a portable design trying to stay fanless, and a powered desktop design willing to use active cooling for capacity and sustained-load potential.
Micron and Crucial should not be conflated here. Micron is the parent company and Crucial its consumer brand; the CES report situated the prototypes alongside Micron’s consumer SSD activity, but it did not confirm a Crucial-branded launch. Nor does the absence of these concepts from Micron’s current public catalog prove a formal cancellation. The supportable conclusion is that they remain CES demonstrations, not publicly listed retail products.
Who would benefit from this class of drive?
A USB4 SSD is most useful when the host has a matching high-speed port and the work involves frequent, large transfers—such as moving video projects, large creative assets, or using an external scratch drive. For occasional backups and ordinary document storage, a less expensive 10Gbps or 20Gbps drive may be more sensible. A USB4 NVMe enclosure gives more choice over the internal SSD but requires attention to compatibility and thermal design; a prebuilt unit is simpler but fixes the drive and cooling arrangement. Internal PCIe storage is preferable when portability is unnecessary, while network storage is a better fit for shared access and centralized backups.
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Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Whichever route you choose, consider sustained rather than just peak speed, capacity, price per terabyte, fan noise, warranty, firmware and utility support, and portability. A cable mismatch or slower host port can erase the expected speed advantage; extended transfers can expose thermal throttling or cache exhaustion; and a laptop’s power budget can matter for bus-powered devices. Micron’s CES concepts were useful precisely because they highlighted these system-level constraints, not because they established a product anyone could buy.
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