Sorry I'm sad to say that this was of no help to me, maybe because it wasn't detailed at all, or the fact that it didn't work at all "for me". Please review this tutorial to make it useful for others.

I have your same video card...but I get an average of 90 fps out of smoke. Maybe you should take a look at your processor. Good tutorial btw.

For those who are struggling to understand this very simple instruction, the english is not that poor...

1. Create a nodraw texteured box where you want the fog to be. The size of the box is the size of the cloud, so the bigger it is, the bigger the cloud will be.

2. Right click on the box, select tie to entity and set it as a func_dustcloud.

3. Edit the settings (they are very clear and concise, so you won't need any help here.

4. Compile the map and there is your fog.

(Freeman 212 you need to learn proper English before criticising others).

Just not up 2 scratch