1. Uninstall your nvidia video drivers from control panel.
2. Run Driver Sweeper http://www.guru3d.com/category/driversweeper/ and wipe all the left over video driver files from Nvidia.
3. Take out your 560 and install the 2 580s with the SLi brigde.
4. Enable SLi in nvidia control panel
5. Download and install new Nvidia Driver.
6. Wipe drool from mouth from all the eye candy in games.