The NVIDIA Geforce 7950 GX2 and the Geforce 7900 GX2 dual GPU graphics cards are designed to take advantage of NVIDIA's newest Control Panel. Certain new features available for the Geforce 7950 GX2 and the Geforce 7900 GX2 are only accessable through the new NVIDIA Control Panel. If you are running in Classic Mode, you will not be able to make certain changes to your NVIDIA display properties including switching between "Multi-GPU mode" and "Multi-display mode". Please revert back to the new NVIDIA Control Panel by following the instructions below:
1) Open the Microsoft Windows Display Properties by Right-Clicking over any part of your Desktop -> from the pop-up menu, choose "Properties"
2) This will bring up the Windows Display Properties. Left-click over the "Settings" tab and then click on the "Advanced" button below to access the Advanced Display Properties
3) From within the advanced section of the display properties, click on the tab to the corresponding graphics card you are using. From the left pull out window, choose "Control Panel User Interface". On the right panel, you will see screen similar to the image below. Choose "New NVIDIA Control Panel (Recommended)" and then click on the "OK" button.. A window will appear asking you to confirm your selection. Choose "Right Now".
4) This will bring up the NVIDIA Control Panel. Choose the "3D Settings" button.
5) Next, select the "Set multi-GPU configuration" link
6) This will bring up the "Set Multi-GPU Configuration" page where you may switch between "Multi-display mode" and "Multi-GPU mode".