How can i activate it? Forcing via driver did nothing.

I use this, but i use a console var to enable it instead of forcing it by driver (because it should give better performance). The console var is r_TexMaxAnisotropy, and i put it in the system.cfg file in Game subdirectory of Crysis; if system.cfg doesn't exist, create it. For example, add in the cfg r_TexMaxAnisotropy=16 to set the anisotropic filtering to 16x.