open app manager and there is app called max cpu. you can overclock easily with it. if you want to do it manually then open filebox or any other 3rd party file manager with root access. navigate to usr/share/kernel-power-settings. there is a text document default. default min freq is 250 and max is 600 change max to anything u like e.g 900 and it will be overclocked to 900 mhz.