Skype 5.0 and higher for Windows uses Microsoft DirectX, which makes use of the hardware acceleration features of modern graphics adapters. If DirectX 9.0c or higher is not installed on your computer, Skype can make use of Windows' basic graphics capabilities, but this places additional demands on your CPU, and can cause Skype to run slowly. To avoid this, and to ensure the best performance when making video calls:
To check whether DirectX 9.0c or higher is installed on your computer:
On the System tab, in the System Information area, next to DirectX Version, check the version number displayed. If it is 9.0c or higher, proceed to the next step. If it is lower than 9.0c, you will need to upgrade. For Windows Vista and Windows 7, get the latest version of DirectX by updating Windows with the latest service packs and updates. For Windows XP, download it here.
If the DirectX Diagnostic Tool does not open, or an error is displayed, then it is likely that you do not have DirectX installed on your computer. Download and install it using the links above.
Remember to restart your computer after installing or updating DirectX.
To update your graphics adaptor drivers, you will need to know the make and model of your computer. Once you know this, visit the manufacturer's website and download the latest graphics drivers, usually found in the support section. Make sure that you get the correct drivers by searching for the specific model number of your computer.
Popular graphics adaptors are:
If you cannot find your graphic adaptor, you can also try to update your graphics drivers using Windows Update. Remember to restart your computer after updating your graphics drivers.
After updating your graphics drivers, check again that DirectX 9.0c or higher is correctly installed on your computer.