The PEXUSB3S4V PCI Express USB (Universal Serial Bus) 3.0 Card (with SATA Power) adds 4 external USB (Universal Serial Bus) 3.0 ports to any PCI Express-enabled computer system with support for data rates up to 5 Gbps, while remaining backward compatible with USB (Universal Serial Bus) 2.0 / 1.x devices. Enhanced with UASP support (USB Attached SCSI Protocol), this USB (Universal Serial Bus) 3.0 controller performs up to 70% faster than conventional USB (Universal Serial Bus) 3.0 when paired with a UASP supported enclosure (Note: UASP requires a compatible operating system). Using a more efficient protocol than the traditional USB (Universal Serial Bus) BOT (Bulk-Only Transport), UASP technology optimizes transfers by allowing multiple commands to be processed simultaneously, significantly increasing transfer speeds for less wait time on data transfers. See our UASP test results below for further details. The card uses a "stacked" port layout that places the ports one on top of the other, enabling all four USB (Universal Serial Bus) 3.0 ports to be external facing, while still allowing the card to fit into a small form factor/low profile computer system using the included low profile bracket. Plus, with a built-in SATA power connector, each USB (Universal Serial Bus) port can provide up to 900m A of power to devices that draw power from a host bus connection (500m A for USB (Universal Serial Bus) 2.0) by connecting to your computer power supply. Backed by a Star Tech.com 2-year warranty & free lifetime technical support. enhanced Performance with UASP UASP is supported in Windows 8, Server 2012 & Linux kernel 2.6.3 or later. In testing UASP performed with up to a 70% faster read / 40% faster write speed over traditional USB (Universal Serial Bus) 3.0 at peak performance.