What kind of games is he playing? What settings does he want to run them at? What is his budget? Having no info, my recommendation would be a gtx 650 ti. It runs slightly lower than your gpu and costs around $150. Should be able to run BF3 at Ultra around the resolution at about 60 fps. If you leave some more info (his budget, games, settings for games, etc.), then I may be able to give a better recommendation.