so i need to upgrade my gpu and im not sure which to get. im going to be playing alot of bf4(i game at 1080p) and i know amd cards work well with it but is it worth getting amd just for that and is mantle gonna even help as much as people are saying? my budget is 300-400. im stuck between the 280x 770 and if the 290 better coolers are coming soon (i havnt seen any yet) id probably get one of those. any suggestions