3 ms·

A USB3 A connector has 9 pins, not 4 like USB2, so there are still 6 left.

• snops 8y ago
  And those 6 pins are separate TX and RX pairs, and 2 grounds. The pins disconnected are 5V, which would potentially damage things or cause an overcurrent flag to trip (turning off both ports) if this was connected on both ends, and D+/D-, which is the bidirectional USB2.0 data pair that normally has fixed host/device roles and needs a special controller (like the one in your phone) to be dual role, so it's easier to just disconnect it. The USB3.0 TX/RX pairs are only one way each (think like RS232 null modem but much faster), so it's much easier. This is a good example of how USB3.0 works almost like a separate, parallel bus to USB2.0.