Overclocking is basically making a computer run faster than it is rated to. This has several drawbacks
- More heat produced needs to be removed
- Less stable till you get it right which can take days
- Takes ages to get it right.
- if you get it wrong you will end up replacing parts and that costs a lot.
Plus sides are really only
- 1-2fps in most games. Some only even manage 0.5fps more after an overclock. It isnt worth it in my opinion having tried it as the risk of killing the parts is high. It is better just to get a new processor/ram/gfx if you really need that boost.