Have you looked on your motherboard web site for new win 7 drivers? Win 7 doesn't have USB 3 drivers built in so you have to install them from the web site for motherboard or if PC is a brand name, from the web site for the device.
using them might be fun, one way to get them onto PC while USB doesn't work is use a DVD drive if you have one, or put hdd into another PC and download the drivers and place them on the hdd. then install hdd in new PC again and run the driver installers.