Here, use this because bits of old Catalyst drivers still lying around can cause system instability:http://sites.amd.com/us/game/downloads/Pages/catalyst-uninstall-utility.aspx
I had a similar upgrade to you but I went from 2 x Radeon HD 4870s in crossfire to my HD 7970. Run that tool, it will remove ALL ATi software from your computer including your registry and your AppData. That will ensure a perfectly clean install. Install driver set 13-9 after you restart the computer and all should be well. If that doesn't work, the card is defective.