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?
Best Answer
Basically they're physically incompatible on the motherboard side, but there's very little stopping a USB 2.0 device or connector being used with a USB 3.0 header with an appropriate adaptor - a quick google search reveals there's quite a few appropriate adaptors with a USB 3.0 female to USB 2.0 male adaptor.
If you want a USB type A Male to usb male header, for use with that PCI cards try this search. You should be able to plug in the header on the device side to the male header, and plug that right in.
So yes, physical incompatibility aside, USB 2.0's pin out is a subset of USB 3.0, and with the appropriate parts, you can, in fact, plug in a USB 2.0 plug into a USB 3.0 header on the motherboard.