You could probably get away with a Pentium G4560. It has hyperthreading enabled, so it's basically an i3 at almost half the price. For most FPS games, you don't need a more powerful CPU, you need a faster GPU (CPU intense things like Shadows and Physics aren't all that intense in most popular shooters and in all honesty, that Pentium should be powerful enough to run physics at medium to high, depending on the game). Put the money saved on the cpu into a good GPU and mobo. The Pentium can be easily replaced down the road if you need a better CPU, but the GPU will need to be fast from day one to enjoy your games. And make sure you get a good motherboard. I promise, you'll probably have the mobo for much longer than the GPU and CPU.