SuperSpeed USB 3.0 supports transfer rate of up to 5Gbps - The actual transmission speed is limited by the setting of the device connected. * 2 USB 3.0 downstream ports for standard desktop PCs. * Backwards compatible with USB 2.0 and 1.1 devices. * 5V 4 pin connector to power USB devices from your PC power supply; The PCI-E Port only support PCI-E X1/X16 slots. * Operating System Compatibility: Windows XP/Vista/7/8.