For buyers weighing this enclosure against alternatives, it's worth knowing where the ASM2464PD chip sits in the broader landscape of SSD enclosure controllers. A well-maintained independent reference (Dan S. Charlton's tech blog) puts real-world numbers on the major chipset families:

A few useful takeaways for anyone comparison-shopping:

• The ASM2464PD and Intel's JHL9440 (Thunderbolt 4) land in the same real-world performance tier — so a Thunderbolt 4-based competitor isn't inherently faster, just differently certified. The real jump in speed only comes from Thunderbolt 5 (JHL9480), which roughly doubles throughput but requires a TB5-equipped host system — still rare as of this review.
• Many enclosures marketed as "USB4 compatible" are actually older Thunderbolt 3 (JHL7440 or even older Alpine Ridge) designs underneath, which cap out meaningfully lower (~2.6–2.8 GB/s) than genuine ASM2464PD or JHL9440-based products (~3.2–3.8 GB/s) — worth checking the fine print/chipset spec before assuming "USB4" branding alone guarantees top-tier speed.
• The ASM2464PD chipset is used by numerous other brands beyond UGREEN, including Acasis, AData (SE920), Hyper (NextDrive), JEYI (TB2464), Maiwo, Orico (TCM2-U4), OWC (Express 1M2), Satechi (ST-EU4NPM), and several lesser-known AliExpress-sourced brands (Colorii MC40 / Qwiizlab ES40UR / Hagibis MC40, which appear to be the same OEM design sold under different names) — most share very similar PCB designs and near-identical performance, meaning brand choice often comes down to build quality, bundled accessories, price, and firmware support rather than raw speed potential.
• A known host-compatibility gap: 11th-generation Intel CPUs (including the Surface Laptop Studio) reportedly don't play nicely with the ASM2464PD chipset — some systems either fail to detect the enclosure at all or fall back to as little as ~4Gbps. If your PC uses an 11th-gen Intel CPU, a Thunderbolt 3 (JHL7440-based) enclosure may be the safer choice instead.
• A second host-side quirk reported independently: on some Thunderbolt 4/USB4 motherboard setups, moving the enclosure to a different port or swapping cables can require re-entering BIOS setup (sometimes twice) before the system recognizes the boot drive again, and can also silently reset the Windows write-caching policy back to its default — worth checking if a firmware update doesn't fully explain an unexpected performance or boot change.

If budget is the primary concern rather than maximum speed, JMicron- and RealTek-based enclosures (JMS583, RTL9210B, and similar) are considerably cheaper but cap out around 875 MB/s — a large step down from the CM642's ASM2464PD performance, but fine for less demanding use cases like general backups or slower HDD/SATA SSDs.

Conclusions

The UGREEN CM642 is a well-built, genuinely fast USB4 enclosure that earns its reputation across independent lab testing, official specs, and hands-on real-world benchmarking alike. But one practical recommendation now stands above all others, backed by this review's lab testing, the Reddit community's findings, and a broad, independent sample of 2026 Amazon buyer reviews alike: budget for a separately-purchased, certified 40Gbps USB4/Thunderbolt cable from day one. The single biggest gap between buyers who love this enclosure and buyers who return it isn't the enclosure's hardware — it's the bundled cable, which underdelivers often enough to be the default expectation rather than a fluke. Treat a quality cable as a mandatory part of the purchase, not an optional upgrade.

With that sorted, on Windows with a modern USB4 host, this is an easy recommendation — you'll get some of the best real-world USB4 speeds available at this price point, with an actively maintained firmware path if you ever need it.

On macOS, and on any older Thunderbolt-3-only host, temper that enthusiasm. The ASM2464PD chipset can suffer from intermittent disconnection issues that don't have one reliable fix, and that M1-generation Macs and other Thunderbolt-3-only hosts may not reach full speed at all. Firmware helps some users and makes things worse for others; cable choice matters as much or more than firmware version; and both a plausible mechanical cause (a soft retention peg that can loosen under heat) and inconsistent fan/thermal performance across individual units have been identified independently of any software issue. If you're on a Mac or an older Thunderbolt-only PC, budget time for troubleshooting, keep your return window in mind, and know that a different enclosure using the same chipset (several buyers found Satechi more reliable, others found it no better) is a legitimate fallback if this one doesn't settle down for you.

Pricing

Around €80–100 on UGREEN's own EU store (frequently discounted from a €99.99 list price), or ~$110 US at review time (street price often closer to $75–80 on Amazon). Since it's a bare enclosure, budget separately for a drive — anywhere from ~$40 (256GB) to $650 (8TB), with the best value sitting in the 1–2TB range. There's little reason to pay for a Gen5 or even Gen4 drive specifically for this enclosure, since USB4's 40Gbps ceiling can't take advantage of the extra bandwidth — a good Gen3 TLC drive performs nearly identically here.

Pros & Cons

Pros:

• Genuinely class-leading, independently verified USB4 real-world performance
• Solid, attractive aluminum build with a distinctive copper accent
• Full 40Gbps support on Mac (unlike many USB 3.2×2 rivals, which throttle on Thunderbolt ports)
• Tool-light, easy drive installation (2230–2280 support)
• Effective active cooling — confirmed under sustained load with real temperature data
• Zero driver friction for normal use
• Bridge chip firmware is actively maintained by ASMedia, with a real (if unofficial-from-UGREEN) update path
• Real-world reports of 8TB drives working fine are a good thing

Cons:

• Non-captive case screw — easy to misplace
• The included cable frequently doesn't deliver full 40Gbps — this is the single most common buyer complaint across many users for MacOS systems; budget for a separately-purchased certified 40Gbps/USB4/Thunderbolt cable as a near-mandatory extra cost
• Some users may find exirsting fan effectiveness and heat management questionable
• The M.2 mounting screw's single-piece capture+standoff design isn't clearly explained in the instructions and has confused multiple buyers during installation
• Double-sided/thicker NVMe drives may not fit with the included screw — check your drive's thickness first
• No official UGREEN firmware support or documentation — you're relying on the chip vendor's tools instead, a real obstacle for Mac-only households without access to a Windows PC
• Auto-sleep can't be disabled while running in native USB4/Thunderbolt mode
• macOS users report a real, long-running, and inconsistently-resolved disconnection issue with this chipset family — firmware updates help some users, hurt others, and cable/thermal/mechanical factors are frequently the actual culprit instead
• Older Thunderbolt-3-only hosts (M1-generation Macs, some Titan-Ridge-based PCs) may fall back to USB 3.x speeds or fail to connect at full speed, despite "Thunderbolt 3" appearing in the product's compatibility marketing