The GTX 670 isn't overkill at all, actually you should be able to max out bf3 with it on 1080p (with aa on max) and you should hold around 60 fps average. Not to mention if you overclock it a bit. Honestly that is my favorite gtx 670 card, so i can strongly recommend it. If you're into overclocking, it does it like a champ.
Oh, the only way it would be over kill was if you had like a 1680x1050 monitor or something like that. But even if you did i would still recommend this card to you, it works wonders