download the ahci driver, its an exe that extracts. go into the extraction and find the x64 diver folder then copy it to a usb drive. then when u get to the screen on the windows install were u select the drive click on advanced then load driver and load.
http://game.amd.com/us-en/drivers_ca...ista32-chipset

it will also be on the disk that came with the MB but i like this way better