Hard to say how much fps we would be talking, as it really depends on whether the title is CPU or GPU bound. Most triple A titles mainly benefit from GPU. I would guess maybe 5-10 FPS to 40+ depending on title, but it I wouldn't upgrade it purely based on gaming performances. That said, if you intend to do CPU based streaming, without having a dedicated PC for it, I would definitely look into a 6 or 8 core CPU. Currently there aren't that many great options on those, but Ryzen 3rd gen should hit later this year (Like Q2-Q3ish). Unfortunately there isn't really an upgrade available on 1150 socket, so you would have change mobo (And ram cause of DDR4) so it would get rather pricey.