hay i have the same problem but i tried that and it still wont let me select it i have a 670 btw so it should run dx11, however i do have a beta drive but it says its like 36% better than previous drivers on far cry 3 so it must be dx11 compatible. hope you can help !
if your running the exe listed above then the game will run dx11. if it fails then check your event logs and see if your drivers are failing. also next time make your own topic. as this 1 has been solved so if i hadent come looking it wouldnt be getting answered.
look in the install folder you should see a file called farcry3_d3d11.exe
run that as admin and the game will start in dx11 mode.
im having this issue too, but i can not fine the FarCry3 install file that has the farcry3_d3d11.exe file in it.
Could you please tell me where to look to find it. (far cry 3 is on Uplay, not Steam if that helps)