[COM | Rushin'n]

1 First open the steam window and click games
2 now right click on counter strike source and then click properties
3 A window should pop up
4 From here click "Set Launch options"
5 A small window will come up ...

EXAMPLE " -dxlevel81 -tickrate 100 -gl

-dxlevel 90 = Directx 9.0
-dxlevel 81 = Directx 8.1 =best...Graphics and performance!!!!unless you have uber fast comp wit no lag..Geno.....!
-dxlevel 80 = Directx 8.0
-dxlevel 70 = Directx 7.0

-tickrate 100 smooths it all out....

-gl use if u have a NVIDIA graphics card....
-d3d use for ATI gfx card

-refresh "Refresh Rate"= only use if you know what your monitor can handle...