Intel's new hardcore overclocking CPUs can hit some amazing core speeds with a cheap air or water-cooling system. They're built for speed, and unlocked to achieve those figures easily if you have the interest and technical know-how. One point of order, though -- if you're buying a new top of the line Core i5 or Core i7, you won't get a cooler in the box.
The new Intel Core i7-6700K and Core i5-6600K chips, out in Australia now for $579 and $399 respectively, don't include a standard Intel low-profile air cooler in the newly redesigned retail box. Interestingly, the previous (4th generation) stock Intel heatsink is not compatible with the new chips, although we've been told by third parties that their aftermarket coolers -- like the Noctua D15 air-cooling tower or Corsair's H100i closed-loop water cooler -- will still work without any adapting kits needed.
Intel suggests you buy its new TS15A air cooler if you're running your new K chip on stock speeds, TS13X water cooler if you're intending to boost clocks and voltage and make a bit more heat. Since the new Intel chips have a TDP of 91W versus old K-CPUs' generally 130W profile, you should have a lot of headroom on either of these, or any aftermarket cooler, without stressing the thermal design of your heatsink.
This news is specifically for the new Intel unlocked-multiplier K-SKU CPUs, the ones made for serious overclockers and hardcore gamers -- the crowd that usually has an aftermarket cooler bolted on anyway. To be honest, I've lost track of how many CPUs I've bought where I've just put the stock Intel cooler to the side and then forgotten about it forever. If you're an enthusiast, you've likely done the same thing, so no big deal. [Intel]