Next stop should be a guide for your particular motherboard. Google is your friend.
Which CPU works faster on directx 11 games?
E7400 (stock) or E7400 (OC) or Q8300 (stock or OC)
Obviously, an OC'd E7400 will work better than an E7400 running at stock freqs. The Q8200 CPU family is not known for being great overclockers. You should be able to push the E7400 much higher. The only thing that might make a difference here is if the games that you are interested in support quad cores CPU's