小弟的狀況跟這位網兄一樣...

I also tried sweetfx, there's a version of 1.5 floating around that claims to be 64 bit and win 8.1 compatible. All of the sweet effects worked... except SMAA. Once again smaa clearly doesn't get applied when I toggled sweetfx on/off. all the other effects did, and I made sure smaa was enabled in the sweetfx config. For some reason I just cannot get any form of smaa working in bf4 in win 8.1...

http://forums.guru3d.com/showthread.php?t=384954