If you are talking about USB3 then for that case they are designed to be poked through one of the grommets in the back of the case and plugged into the motherboard I/O backplate externally.
I don't know of any adapters available to connect them internally, but someone might? Other cases are now beginning to support usb3 natively like the Fractal Design ARC and the CoolerMaster Storm Enforcer. These both have internal usb header connections.
This isn't on topic, but I am tossing around the idea of buying the Haf-X for the build I am doing in about a week but am curious on what the cable management is like, could you give me some insight on this?
This isn't on topic, but I am tossing around the idea of buying the Haf-X for the build I am doing in about a week but am curious on what the cable management is like, could you give me some insight on this?