Direct X levels on the Source Engine

[Mabrito]

Im know this probably has been asking many times before. I did a search for it, and couldnt find anything, so here it goes.

What is the command to change Direct X levels? I know you are suppose to enter it in startup options, under the game, or some config file. I just need to know what to type in, to get to change. I want to go from Direct X 9 to Direct X 8 levels, for smoother game play.

 

[scottemad123]

in the properties line do -dxlevel 70, or 80, 81 or 90 for the different levels. in game do mat_dxlevel 70 etc in console