For gaming an i5 would be a better cpu, it's much cheaper and gives the same performance as the i7s on the 1156 socket. Hyperthreading only makes the i7s slightly better then the i5 in 5 threads and above, but games don't usually use more then 4 threads(and they won't get more threads until many years from now).
Yes, hyperthreading does make the i7s use slightly more power(at the same clock speed if using the extra threads from hyperthreading) then the i5.
If you ever wanted to overclock the i5 would overclock to the same clock speed.