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Sonnet Technologies

Allegro 2-Port USB-C
SuperSpeed USB 10GBps PCIe Card with USB-C Charging

Mac / PC / USB 3.1 Gen 2
Low-profile Dual-port With 15W Power Per Port
Add SuperSpeed USB 10GBps Technology
Up to 2X as fast as USB 3.0 connections
When it comes to supporting the fastest USB drives available, your computer's USB 3.0 ports are perfectly adequate… for connecting peripherals that don't depend on the ultimate USB 3.1 speeds. However, common USB 3.0 ports can be underachievers — at 5Gbps, they can't support the maximum performance from many storage devices, and may not provide enough power to enable them to operate. You need SuperSpeed USB 10GBps. You need Sonnet's Allegro USB-C PCIe card.

The Allegro™ USB-C PCIe supports data transfers at up to twice as fast as USB 3.0, and can also deliver 15W of power per port to USB-C bus-powered devices (three times the 4.5W specified in the USB 3.0 spec). Don't settle for mediocre performance or insufficient power for the fastest SSDs — install an Allegro USB-C card to instantly add two Gen 2 USB 3.1 ports to your system and take full advantage of today's SSD performance.
Speed and Power
Sonnet's Allegro USB-C PCIe computer card supports data transfers up to 960 MB/s when connected to a USB-C Gen 2 SSD RAID device — transfers complete in half the time compared with using a USB 3.0 2.5-inch SSD! Sonnet specially engineered the Allegro USB-C card to provide 15W of power through each of its ports. The ports communicate with the host that 3A of VBUS current is available, enabling this Sonnet solution to support USB-C bus-powered SSDs and SSD RAID devices that need 15W during demanding write operations.
Regulates Power to Each Port
Ordinary USB-C adapter cards deal with power delivered through the ports as an afterthought, requiring an additional power source for the card and providing little regulation. The Allegro USB-C PCIe is no ordinary adapter card. The Allegro card regulates its own power without requiring a back-of-the card power cable connection, thus enabling full compatibility in any computer or Thunderbolt expansion chassis that doesn't have these power connectors available.

Sonnet's Allegro USB-C is unique in regulating power to each port independently, giving each one protection from power glitches on the adjacent port. Without this protection (such as found on an ordinary card), connects and disconnects of one device may cause auto-disconnects of the other.
Resettable Fuses
The Allegro USB-C card features a resettable fuse on each port to protect the card and computer should there be a cable or peripheral failure. Should a fuse trip on the Sonnet card, you can reset it simply by shutting down the computer.
PCIe Auto-Negotiation
Sonnet's Allegro USB-C PCIe features PCI Express auto-negotiation. The card automatically negotiates to a x1 data link in a PCIe 3.0 slot, and to a x2 link in a PCIe 2.0 slot, giving full bandwidth to both generations of PCIe slots, ensuring great performance in any configuration.
Optimized for Thunderbolt™
Got a Thunderbolt connection, but no PCIe slot? The Allegro USB-C PCIe card is ideal for use in any Thunderbolt 2 or Thunderbolt 3 to PCIe card expansion chassis, including Sonnet's Echo Express™ or xMac™ Thunderbolt to PCI Express card expansion systems, offering full performance wherever you install it — now you can add dual USB-C ports in any current Sonnet Thunderbolt chassis.
Easy Installation
This Allegro USB-C PCIe card installs easily into any PCIe x4 (mechanical) slot; both low-profile and full-height mounting brackets are included. The Sonnet card features hot-pluggable and hot-swappable device connection support with automatic device configuration, and works with all USB-IF compliant USB peripherals.

Product Specifications:

Sonnet Technologies Part Number

  • USB3C-2PM-E


  • ASMedia 1142


  • (2) External USB 3.1 Gen 2


  • PCI Express 3.0 x1 auto-negotiate
  • Also supports PCI Express 2.0 x2

Chipset Throughput

  • 10 Gbps combined port throughput

Software Requirements

  • OS
    • OS X 10.10.5, macOS 10.12.6 or later, macOS 10.11 is not compatible
    • Windows 7 or later
    • Windows Server 2008 (64-bit Edition) or later
    • Linux 4.12+ Kernel2 (LTS version only)

Hardware Requirements

  • Minimum
    • Mac or PC featuring PC with a PCIe 2.0 x2 slot
  • Recommended (Best Performance)
    • Mac or PC featuring PCIe 3.0 or higher slot
  • Thunderbolt Compatibility
    • Supports USB 3 peripherals on a Mac or Windows PC when installed in a Thunderbolt 2 or Thunderbolt 3 PCIe expansion system3


  • No computers support booting at this time

Peripheral Support

  • Industry standard USB 3.1 Gen 2, 3.0, 2.0, and 1.1
  • Not compatible with Thunderbolt 3 peripherals

Bus Power Peripherals Support

  • HD, SSD, SSD RAID, DVD & Blu-ray devices
  • 3A per port advertised using USB-C CC (Channel Configuration)
  • Up to 15W per port for operation or charging

Cables Support

  • USB-C 10Gbps
  • USB-C 5Gbps
  • Thunderbolt 3 40Gbps (0.5-meter only)
  • Thunderbolt 3 20Gbps


  • Supported under macOS 10.10 & 10.12+, Windows 10

Standards Support

  • OHCI
  • EHCI
  • xHCI

RoHS Compliance

  • Yes

Form Factor

  • PCIe x4 low-profile computer card; full-height mounting bracket attached, low-profile bracket included


  • macOS erroneously reports a 5Gbps connection when connected at 10Gbps
  • Linux supports only 5Gb transfer rate as of 4.12.13 Kernel
  • Not compatible with Thunderbolt 1 PCIe Expansion systems
Manufacturer provided specifications for Sonnet Technologies p/n USB3C-2PM-E UPC#: 732311012136
This product is compatible with... Learn how to find your Mac's model ID
Mac Pro
Mac Pro 12-Core (Mid 2012)
(June, 2012)
Model ID: MacPro5,1
2.4GHz, 2.66GHz, 3.06GHz
Mac Pro
Mac Pro 6-Core (Mid 2012)
(June, 2012)
Model ID: MacPro5,1
Mac Pro
Mac Pro 4-Core (Mid 2012)
(June, 2012)
Model ID: MacPro5,1
Mac Pro
Mac Pro 12-Core (Mid 2010)
(July, 2010)
Model ID: MacPro5,1
2.66GHz, 2.93GHz
Mac Pro
Mac Pro 8-Core (Mid 2010)
(July, 2010)
Model ID: MacPro5,1
Mac Pro
Mac Pro 6-Core (Mid 2010)
(July, 2010)
Model ID: MacPro5,1
Mac Pro
Mac Pro 4-Core (Mid 2010)
(July, 2010)
Model ID: MacPro5,1
2.8GHz, 3.2GHz
Mac Pro
Mac Pro 8-Core (Early 2009)
(March, 2009)
Model ID: MacPro4,1
2.26GHz, 2.66GHz, 2.93GHz
Mac Pro
Mac Pro 8-Core (Early 2008)
(January, 2008)
Model ID: MacPro3,1
2.8GHz, 3.0GHz, 3.2GHz
Mac Pro
Mac Pro 4-Core (Early 2008)
(January, 2008)
Model ID: MacPro3,1
PC Desktop
PC running Windows, Linux or FreeBSD and available PCI-Express x4 lane or better slot
OWC Helios
OWC Mercury Helios 3
Thunderbolt 3 PCIe
expansion chassis
OWC Helios
OWC Mercury Helios
Thunderbolt PCIe
expansion chassis

Customer Ratings

Write a Review 3 / 5 2 out of 3 (67%) reviewers would recommend this product
Verified Buyer
Reviewer: Sergey7084 Location: Moscow, Russia Age: 45-54 Experience Level: Power User Owned Product: less than a month
Rating: 5/5 High reliability and stability July 29, 2020 This board just works as it should work without glitches and any nuances.

I would recommend this item to a friend!

Verified Buyer
Reviewer: jb606 Location: Chicago, IL. Age: 35-44 Experience Level: IT Professional Owned Product: over 6 months
Rating: 3/5 Adds much needed USB 3.x to my 12yr old Mac Pro 3,1 June 14, 2020 I'm most definitely not getting the rates advertised by USB 3.1/Gen2, but it's certainly at least 3-5x faster than the USB/2.0 ports on my 2008 Mac Pro 3,1. I should mention that I'm running Catalina via the DosDude1 patch, which may also have an effect on speed.

The previous reviewer mentioned the "Disk Not Ejected Properly" error: This is an issue with the OS, and not the card itself. A quick google search should show you how to resolve this (it's not unique to the Sonnet card).

I would recommend this item to a friend!

Verified Buyer
Reviewer: Maric Location: Portland, OR Age: 45-54 Experience Level: IT Professional Owned Product: less than a month
Rating: 1/5 Disk Not Ejected Properly December 22, 2018 The card has a poor fit, the ports sit too close to the separator between cards. Reseating the card helps but it is still a tight fit. The biggest problem with this card is that when the computer awakes from sleep you get a "Disk Not Ejected Properly" error. Sonnet's website states that this is normal behavior and not an issue; to me this seems like a major flaw with this card and it should be documented so that consumers can make an informed choice before purchasing this card.

Sonnet Technologies Allegro 2-Port USB-C SuperSpeed USB 10GBps PCIe Card with USB-C Charging Mfr P/N: USB3C-2PM-E OWC SKU: STIUSB3C2PME Low-profile, dual-port PCI Express 3.0 card delivering 10Gbps combined port throughput and 15W of power per port. Sonnet Technologies 1 Year Limited Warranty Ships: Same Day Only $99.00OWC Price $77.99
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