In this picture (originally posted in this thread), there are capacitors called "AC Capacitor". Why do I need those capacitors? It is a USB 3.0 SuperSpeed connection, so it would not be an AC-Powered device.
While it's powered by DC, the signals are high frequency differential pairs on transformers to prevent the need for dc coupled devices. The AC capacitors couple the differential pairs between the transceiver and receiver, and managed the dc bias blocking.
See the answer by Some-Hardware-Guy on AC-coupling capacitors for high-speed differential interfaces for a full explanation.