you won't see your gpu's full potential mainly because of your processor, not your motherboard. since you said that your motherboard has an LGA 775 socket, chances are you are using a fairly old processor. but games are still playable and you won't really have fps problems especially on games that aren't so cpu intensive like BF4.
eventually, you're gonna be forced to upgrade to a new motherboard and processor, preferably a quad core, i5 or something like that.