Get the Zalman 9700 or the Tuniq Tower 120 or the Scythe Infinity.
But im warning you! Youre not going to get an overclock that will justify buying a whole new cooler. I have the CNPS 7000Cu and i couldnt be happier. When i get my new PC ill buy something better, but this cooler is great!
Or u could buy a whole watercooling kit for 250$+.