I say save up the extra money you need for an i5, the money you will spend on a new motherboard to overclock your current CPU will cost more than what you will get out of it. You might squeeze out a few extra frames but that's about it. Put it this way, you will probably be disappointed with the extra performance from an overclock especially since you are trying to utilize your 970, where as if you go with an i5 you won't be disappointed.