Hey, I was considering ov3rclocking my CPU and i figured i needed some cooling. So I had an old fan sitting around and I though about it, so I stuck the old fan right behind my case fan, and screwed them together. now I have 2 fans that are " helping each other" push air out. My CPU temperature stays at about 35 degrees Farenheight. You should try it out if you want good cooling for cheap.
make sure the fans push the same direction.