I installed the Corsair H100i and it lowered my temp by 30 degrees celsius. I have a 3930K running at 4 Ghz. I max out at 57 degrees celsius over an hour of Prime 95.
I wouldn't use anything but water , it keeps all the components from overheating when overclocking and will keep them at a constant temp. Of course as with anything there are limits but you can get higher overclocks and lower temps with water.