DirectX is a technology used by multimedia programs running on your system. The DirectX Diagnostic tool (DXdiag) helps you troubleshoot DirectX related issues such as, checking digital signatures for your video card drivers. It also checks whether a driver has passed the Microsoft’s Windows Hardware Quality Labs (WHQL) tests. But most importantly, it helps find problems with games or movies that cannot run properly. The first time you run the DXdiag tool you are asked whether you want to check if your drivers are digitally signed and that the tool may connect to the Internet but no personal data is collected.
Make sure that you select the Check for WHQL digital signatures option in order to test for signed drivers. That is, digitally signed drivers have been tested by the Microsoft Windows Hardware Quality Lab for DirectX compatibility. It is recommended, to update a driver that is flagged as unsigned.
To start the DirectX Diagnostic tool, type DXdiag in the Start search text box and click dxdiag.exe
The System tab displays the version of your DirectX, an option to run the 64-bit version (recommended if your system is 64-bit), save the information to a text file and shows system related information.
The Display tab provides details about your video device and driver. The WHQL Logo’d shows if the driver has passed Microsoft’s quality tests. Make sure that DirectDraw, Direct3D and AGP Texture acceleration are enabled if you are experiencing slow performance with certain programs. You can enable hardware acceleration from the Advanced Settings of the Display\Screen Resolution window. The notes section displays warning message if DXdiag has detected problems, otherwise it shows the text No Problems Found.
The Sound tabs display details about your sound devices and drivers. Each Sound tab refers to a specific device which means that you either have more than one sound card or the sound architecture incorporates different devices. The Input tab lists the input devices connected to your system, such as, USB or PS/2 devices but it does not show device drivers for input devices.
The DirectX Diagnostic tool gives you details about which devices have problems, which drivers are unsigned and the installed version of DirectX. Updating unsigned drivers from the manufacturer’s web site, quite often solve problems. If an old game requires a previous version of DirectX then you have to downgrade your installed version, however, make sure that no updates are available for the game which may solve the problem or make the game compatible with the latest version of DirectX.