mat_dxlevel

mat_dxlevel changes the DirectX mode used within a Source game. The player is only able to use modes that his/her hardware supports. The format is

 mat_dxlevel [DirectX version]
 mat_dxlevel 70
 mat_dxlevel 80
 mat_dxlevel 81
 ...

For DirectX 9 the value depends on the hardware's capability:

 mat_dxlevel 90 - DX9 with Shader Model 2
 mat_dxlevel 95 - DX9 with Shader Model 3
 mat_dxlevel 98 - DX9 on DX10 hardware (SM 4)

This can also be specified with Launch Options, use +mat_dxlevel [DirectX version] on the launch options of any Source game to do so. Alternatively, you can use -dxlevel [DirectX version], however this specifies a number of extra presets, including resolution and quality.

See Also

DirectX Versions