Posted 09 June 2016 - 06:17 AM
Overclocking is exactly what it says, increasing the clock speeds of the CPU, GPU, memory bus, etc so they run faster. The process involves increasing the clock speeds and changing combinations of the clock multipliers (there isn't just a single "clock speed" to change, the multipliers also have to be changed). Along with these changes, it is also common to have to increase the voltage, which in turn creates more heat, which leads to a need for better cooling. "Extreme" overclockers usually end up with expensive liquid cooling set ups to deal with the excess heat.
How much performance gain do you get? It depends on the chip(s) being overclocked and how much of an overclock you can get. Identical model CPU's, for example, will not overclock the same. One will typically will go higher than the other and so on. It's really a luck of the draw in your CPU, although some models in general are better for overlocking. Also, you have to be sure your CPU is not a "locked" model (meaning it isn't overclockable).
Actual performance gains can be decent with the right CPU, but on average it's a few percent increase, up to maybe 10-15% on the high end. The question is, is it worth it? If you're a hardcore gamer looking for every last extra frame you can get, then maybe. For day to day stuff, not so much.
One thing to keep in mind, overclocking stresses the components and if you aren't careful you can easily fry a CPU, GPU or other parts. Just like bumping the HP up on your car engine, you can get more performance, but the cost is a shortened life span, usually. More stress on the components.
My personal opinion is that overclocking isn't necessary in this day and age and not worth the extra cost or potential headaches, but it's a way to learn more about your system, so go for it if you really want to.