Asus P9D-C/4L - Manual (Page 52)

2-32 Chapter 2: Hardware information
4. USB 3.0 connector (20-1 pin USB3_34)
These connectors allow you to connect a USB 3.0 module for additional USB 3.0 front
or rear panel ports. With an installed USB 3.0 module, you can enjoy all the benefits of
USB 3.0 including faster data transfer speeds of up to 5Gbps, faster charging time for
USB-chargeable devices, optimized power efficiency, and backward compatibility with
USB 2.0.
3. USB 2.0 connector (10-1 pin USB78; A-Type USB9)
These connectors are for USB 2.0 ports. Connect the USB module cables to connectors
USB78. These USB connectors comply with USB 2.0 specification that supports up to
480 Mbps connection speed.