Answer: When using a USB 3.0 port, only the main connector is needed. The small secondary cable is not needed. When using a USB 2.0 port, both connectors might be needed as some computers output less power than others through the USB ports. On some PCs, one USB cable is enough, but to be safe and to avoid write errors, connecting both USB cables is highly recommended. If using only one USB connector, the main USB connector must be used, not the secondary connector (short cable) that is attached to the main connector.