AMD Radeon HD 6970 was released with the Catalyst 10.10, and they worked well. Then AMD released the Catalyst 10.11 which did not support Radeon 6970. Finally, the latest Catalyst 10.12a Hotfix was said to support the Radeon HD 6970 graphics card. However, many 6970 users have suffered from blue screens with 10.12. So try 10.10.