Head-to-head · Best External SSD Enclosures

ACASIS USB4 40Gbps NVMe Enclosure vs OWC Express 1M2

Which is the better buy? Side-by-side on rating, price, strengths, and watch-outs — with the published ratings we averaged to get there.

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The short answer

OWC Express 1M2 comes out ahead by a narrow margin (4.4 vs 4.5). The gap is mostly about power users who need high-speed external storage and don't mind the bulk — read the strengths below before deciding.

Ranked #2 in Best External SSD Enclosures

ACASIS USB4 40Gbps NVMe Enclosure

4.4

1 source$75.99as of Aug 1

The ACASIS USB4 40Gbps NVMe enclosure is an aluminium single-drive M.2 case built around an ASMedia ASM2464PD bridge, with an active fan on top of a shell that already works as a heatsink. BestChoices lists it in its Acasis 40Gbps NVMe enclosure comparison. The draw is a 40Gbps path on hosts that support USB4, tool-free installation and temperatures well below what plastic enclosures reach; the costs are an audible fan under load, no encryption and no RAID.

Strengths

— Supports Thunderbolt 4/3 and USB4 for up to 40Gbps connection speed with consistent sustained throughput under long transfers
— Active cooling fan and thermal pad provide excellent temperature control during high-load operations
— Easy tool-free installation with click-fit 2280 NVMe drive insertion and included mounting screws

Watch-outs

— Fan is audible under sustained heavy load which may be disruptive in quiet environments
— No hardware encryption or RAID options—single-drive use only
— Some early firmware polish needed for maximum compatibility with older USB ports

$75.99 · Check Price on Amazon Full review →

Higher ratedRanked #1 in Best External SSD Enclosures

OWC Express 1M2

4.5

8 sources$78.99as of Aug 1

PCWorld's Jon Jacobi called the OWC Express 1M2 'fantastic' for USB4 storage, citing over 3GBps performance and universal compatibility across USB and Thunderbolt ports. PCMag's Tony Hoffman also praised the performance and the range of ways it can be used, while calling out the large size as a drawback. At $219.99 for the 1TB unpopulated version, it is affordable if you are bringing your own NVMe drive. Power users who need high-speed external storage and don't mind the bulk are the fit; anyone prioritizing portability should look elsewhere.

Strengths

— Over 3GBps transfer speeds with USB4 interface
— Works with all USB and Thunderbolt 3/4 ports for universal compatibility
— Available unpopulated so users can leverage their own NVMe SSD

Watch-outs

— Expensive when loaded with an SSD
— Large size may be cumbersome for portability

$78.99 · Check Price on Amazon Full review →

How they stack up

ACASIS USB4 40Gbps NVMe Enclosure

Against the Samsung X5, the ACASIS lets the buyer choose the drive rather than paying for a bundled one, and against the ORICO Thunderbolt 3 enclosure it adds USB4 and Thunderbolt 4 support. The Sabrent Rocket Nano TB4 is more compact with similar thermals but usually costs more, and the ASUS ROG Strix Arion is smaller, cheaper and considerably slower.

OWC Express 1M2

The OWC Express 1M2 delivers over 3GBps speeds and works with all USB and Thunderbolt 3/4 ports, outperforming the Plugable USBC-NVME in terms of universal compatibility and speed. While the ASUS ROG Strix Arion offers better build quality and RGB lighting, the OWC is more versatile for users who want to leverage their own SSDs. Unlike the ACASIS USB4 40Gbps NVMe Enclosure, the OWC lacks active cooling but provides a more affordable solution for those who don't need the advanced features of the ACASIS model.

Specs side-by-side

Spec	ACASIS USB4 40Gbps NVMe Enclosure	OWC Express 1M2
Interface	USB4.0 40Gbps	USB4
Speed	40 Gbps	Over 3GBps
SSD Support	Thunderbolt 3/4	USB & Thunderbolt 3/4
Material	Aluminum alloy	Aluminum
Cooling	Active fan with thermal pad	Passive
Dimensions	100 x 68 x 15 mm	157 x 100 x 25 mm
Weight	0.22 lb	0.99 lb
Bridge Chip	ASMedia ASM2464PD	ASMedia ASM2364

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