StarTech PEXUSB312A3 2-Port USB 3.2 Gen 2 PCIe Expansion Card

Overview

The StarTech PEXUSB312A3 is a standard-profile PCIe expansion card that adds two USB 3.2 Gen 2 Type-A ports to any desktop or server with an available PCIe x4 slot. Each port delivers up to 10Gbps of throughput independently — not shared across the card — making it the right tool when you need to attach high-bandwidth USB peripherals like NVR backup drives, 4K capture devices, or USB-attached storage to a system whose onboard USB controller is already saturated or underspecced. If you're building out a network video recorder workstation or expanding a surveillance server with additional USB storage tiers, this card removes the bandwidth bottleneck that shared USB controllers create.

Key Features

• 10Gbps per port via USB 3.2 Gen 2: Each of the two USB-A ports operates at up to 10Gbps — twice the ceiling of USB 3.1 Gen 1. On a high-frame-rate camera backup workflow or a fast SSD-based archive drive, that headroom is the difference between real-time transfer and a queue that backs up over a shift.
• ASMedia ASM3142 chipset: The ASM3142 is a well-supported, production-proven controller across Windows, macOS, and Linux. It's not a no-name chip — driver stability matters when this card is running in a 24/7 security server environment where reboots for driver issues aren't acceptable.
• PCIe 3.0 x4 interface: The card uses a PCIe x4 slot running PCIe 3.0, which provides roughly 32Gbps of host bandwidth — well in excess of the two 10Gbps USB ports combined. There's no artificial bottleneck on the host side.
• UASP support: USB Attached SCSI Protocol reduces CPU overhead and latency compared to the older BOT (Bulk-Only Transport) protocol. On a server already taxed by video analytics or VMS processing, lower CPU overhead from storage I/O matters.
• Standard profile form factor, 3.9 × 4.7 × 0.7 in: Fits standard desktop tower and rack-mount server chassis without modification. At 2.3 oz, it's light enough that it won't stress the PCIe slot even in rack environments with vibration.
• Internal SATA power connector: The card includes one internal SATA power input. This is required — connect it to avoid under-voltage on the USB ports. The card's total USB power output is 4.5W across both ports, so plan accordingly if you're attaching bus-powered drives that pull close to 4.5W combined.
• OS compatibility — Windows, macOS, Linux: Supported across all three major OS families. For Linux-based VMS appliances and NVR builds running Ubuntu or Debian, ASMedia ASM3142 support is included in mainline kernels, meaning no third-party driver installation in most cases.
• Operating temperature 5°C to 50°C: Appropriate for conditioned server rooms and IT closets. Storage temperature extends to -20°C to 60°C, so shipping and warehouse staging in unheated environments won't damage the card.

Integration and Compatibility

The PEXUSB312A3 fits any PCIe x4, x8, or x16 slot (x8 and x16 slots accept x4 cards physically). Verify your VMS server or workstation has a free PCIe x4 or larger slot before ordering — check your motherboard manual if unsure. The card is compatible with surveillance server builds running Windows Server, Ubuntu, and other Linux distributions common in security integrator deployments. UASP acceleration is available when used with UASP-capable storage devices; legacy USB drives fall back to BOT automatically. The 4.5W total USB power budget supports most 2.5-inch USB-powered drives individually, but connecting two high-draw bus-powered devices simultaneously may exceed the budget — use externally powered storage enclosures in that scenario. For broader network infrastructure planning in surveillance deployments, pairing this with a capable switching architecture ensures your server-side storage I/O doesn't become the bottleneck in a multi-camera archival setup. Review our camera and server selection guide for storage throughput considerations when specifying USB-attached archive tiers alongside IP camera systems.

Frequently Asked Questions

Q: Does the PEXUSB312A3 require a SATA power connection to function?

A: Yes. The card includes one internal SATA power connector that must be connected to a free SATA power lead from the system's PSU. Without it, USB ports may not deliver full power or may be unstable under load.

Q: Are the two USB ports independent, or do they share 10Gbps bandwidth?

A: Each port supports up to 10Gbps independently. The PCIe 3.0 x4 interface provides enough host bandwidth to support both ports simultaneously at full throughput without contention.

Q: Which operating systems does the PEXUSB312A3 support?

A: The card is compatible with Windows, macOS, and Linux. The ASMedia ASM3142 chipset has mainline Linux kernel support, making it suitable for Linux-based VMS servers and NVR appliances without manual driver installation in most cases.

Q: Will this card fit in a 1U or 2U rack-mount server?

A: The PEXUSB312A3 ships as standard profile (3.9 × 4.7 in). Most 1U and 2U servers use low-profile slots — verify your chassis bracket requirements before ordering. A low-profile bracket may be required for rackmount server installations.

Q: What is the total USB power output available for connected devices?

A: The card provides 4.5W total across both USB ports. This is sufficient for one bus-powered 2.5-inch drive at a time, but two high-draw USB devices simultaneously may exceed the budget. Use externally powered USB enclosures for dual-drive configurations.

Q: Does the PEXUSB312A3 support UASP?

A: Yes, UASP (USB Attached SCSI Protocol) is supported. This reduces CPU overhead and improves transfer latency compared to the legacy BOT protocol when paired with UASP-capable storage devices.

Jerry Tildsen

The spec I keep coming back to on the PEXUSB312A3 is the PCIe 3.0 x4 interface paired with the ASM3142 chipset — you're getting a host bus that can move ~32Gbps while the two USB ports max out at 20Gbps combined. That margin means you won't see PCIe-side throttling even under simultaneous full-speed transfers on both ports, which matters when this card is running in a VMS server doing continuous archive writes to USB storage.

Technical Highlights:

• 10Gbps per port: USB 3.2 Gen 2 at 10Gbps per port means a 500GB drive archive can complete in roughly 7–8 minutes at sustained read — practical for shift-end backup routines in retail or warehouse surveillance deployments.
• ASM3142 chipset: Well-supported in Linux mainline kernels — no proprietary driver hassle on Ubuntu-based VMS appliances or custom NVR builds. Stability in 24/7 environments is where this chipset earns its keep.
• 4.5W USB power budget: Total output across both ports is 4.5W. That's a real constraint if you're planning to hang two bus-powered drives off this card — you'll need externally powered enclosures for that configuration.

Deployment Considerations:

• The internal SATA power connector is not optional — skip it and you risk unstable port behavior under load. Make sure your server PSU has a free SATA power lead before the card goes in.
• This is a standard-profile card at 3.9 × 4.7 in. Rackmount 1U chassis almost universally require low-profile cards — confirm your server's slot height before specifying this for a rack deployment.

This card fits best in a tower-format VMS workstation or a full-height rackmount server (2U+) where a free PCIe x4 slot is available and the integrator needs reliable, high-throughput USB connectivity for USB-attached archive storage or high-bandwidth peripheral devices on a surveillance server running Linux or Windows.