not many boards with usb3 yet, most expensive ones have it first. you can add a usb3 card later if you ever get any devices that can use it. otherwise your usb2 stuff will run at usb2 speed if its plugged into a usb3 socket. you can get a p55 board for less than a hudred pounds, you will have to check spec for sound. a enermax 625 pro82 psu will do everything you want with 88% efficiency.