Voltage is generated from within the cpu that causes heat. You could have the best cpu cooler in the world, but if you exceed max safe voltage, you can degrade the life of your cpu quickly. The cpu cooler simply dissipates heat. Unlocked K sku's are designed for overclocking so as long as you stay under the specified max voltage for your particular cpu you should be fine. This is especially true if you do not run your computer 24/7.