Overclocking is like boosting your hardware and getting better performance out of it like increasing the clock speed or the Frequency of a cpu but that will need a better cooling you can not heavy overclock on a stock cooler you can like light overclock, most of the people that do overclocking have good cooling because better cooling, better temps, better overclocking and you can push the frequency more, and if u overclock a cpu to 5.0 Ghz it does mean that when you open the pc and open the task manager the Frequency of your cpu will be at 5.0 Ghz all the time it will not get below or over 5.0 ghz