what is the purpose of expansion card
USB port card: Most desktops do have USB ports, but the version of USB they use may be too slow. You may also have more USB devices than you have ports. A multi-port USB expansion card adds high-speed ports to your computer that works faster than simple port-splitters. The latest version of USB is version 3.0, so any USB 3.0 card you install will be backwards compatible with your old USB devices and operate much faster than older ports.