Add 4 Independent Super Speed USB (Universal Serial Bus) 3.0 ports to your PC through a PCI Express slot. The PEXUSB3S400 PCI Express USB (Universal Serial Bus) 3.0 Card adds 4 independent external USB (Universal Serial Bus) 3.0 ports to any PCI Express x 4-enabled computer system, with full bandwidth support (up to 5 Gbps) per port when connected to USB (Universal Serial Bus) 3.0 devices. Unlike other USB (Universal Serial Bus) 3.0 cards, which share the maximum bandwidth between multiple ports, the card offers maximum transfer rates to each device when multiple devices are connected. Further 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. This 4-port USB (Universal Serial Bus) 3.0 card features a stacked port layout, which places the ports one on top of the other, so more ports are able to fit into a smaller space. 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. 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. At the same peak in testing, UASP also showed up to an 80% reduction in required processor resources. Test results were obtained using an Intel Ivy Bridge system, Star Tech.com add-on USB (Universal Serial Bus) 3.0 cards, a UASP-enabled Star Tech.com enclosure, & a SATA III solid state drive.