I have a Gigabyte GA-Z77X-UD3H motherboard which comes with 2 USB 2.0 internal headers (2*5-1 pins) and 3 USB 3.0 internal headers (2*10-1 pins). The two USB 2.0 headers are occupied, as are 2 of the three 3.0 headers.
I have an additional internal USB 2.0 cable that needs to be plugged in. This answer seems to say that the 2.0 connector will not and should not be connected directly into the USB 3.0 header. Can I still use the remaining USB 3.0 header? And if so how (i.e. what kind of adapter)? At this time, I do not feel comfortable playing with the individual wiring.
I also have a PCI USB expansion card which has an internal USB plug. Could this be somehow used to connect the internal USB 2.0 cable, and what kind of adapter would let me do this?