Short answer. Yes. The Phenom is light years ahead of the Athlon ii. Even a triple core Athlon like what I've got gave a noticeable increase in Battlefield 3 multiplayer. I would get a new heatsink though. You won't be able to cool a 125watt TDP Phenom with a 65watt TDP Athlon ii heatsink. It would run too hot. Get something like the Hyper 212+, if you can't find that the arctic cooling freezer 7 pro is a good buy, its £15 in Britain, probably the equivalent out there.