Originally posted by The Baron
See. There are two kinds of "mixed modes." With regards to HL2, you are wrong in that it IS mixing DX8 and DX9 level shaders. Some people refer to the use of _pp flags as a sort of mixed mode, but that's not really mixed mode.
So yes. The NV cards are using mostly DX8 shaders and some DX9 shaders.
There are two mixed modes in HL2. One is DX9 and one is DX9/DX8.