If you are gaming or rendering stuff and so then yes overclocking is worth it, its like extra free peformance so why not do it.
As long as you can keep it cool that it does not go too hot then oc as much as you can.
But get a 240mm or 280mm radiator one, a 120/140mm is too small, it will keep it cool but not much difference then air cooler a 240/280mm will gove you much more headroom