I used to have a 650 before the fan stopped working, I remember getting around 40-50fps on lowest settings in BF4. My CPU at the time was a Phenom x4 955 BE (not that it matters anyways since BF4 is mostly GPU dependent). With a custom BIOS which unlocks the voltage (I highly discourage it), I OC'ed it up to 1280MHz (+222Mhz OC) and got solid 60fps. I wouldn't spend money on a 650 though... It's not really an upgrade from the 645. You would be better off saving up for something like a R7 260x or R9 270(x).