Add 2 USB 3.0 ports to your desktop computer through a PCI Express expansion slot. The PEXUSB3S2 PCI Express USB 3.0 card lets you add two USB 3.0 ports to your PC through a PCI Express slot. Featuring a native NEC PCI Express host controller chipset, the USB 3.0 standard supports transfer rates of up to 5Gbps, while still providing backward compatibility for older USB 2.0 (480Mbps) and 1.1 (12Mbps) devices. Enhanced with UASP support (USB Attached SCSI Protocol), this USB 3.0 controller performs up to 70% faster than conventional USB 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 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. In addition to providing a much faster transfer rate the PEXUSB3S2 USB 3.0 card also supplies 900mA of power per USB port, allowing more and more external devices to operate without the need of an additional power source. Backed by a StarTech.com lifetime warranty and free lifetime technical support. Improved Performance with UASP UASP is supported in Windows® 8, Server 2012 and 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 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, StarTech.com add-on USB 3.0 cards, a UASP-enabled StarTech.com enclosure, and a SATA III solid state drive.