My LCIII is also overclocked. Thus far, I have yet to add any cooling methods at all, and it seems to have been running fine, though admittedly I don't use it super often or for very long at a time. That said, I do want to add at least a heat sync. Certainly an extra fan as well can't hurt! Different individual CPUs will run hotter or cooler, from what I understand, so if yours was running particularly hot after overclocking, it may be you've done the exact right thing with the additional cooling.