In addition to my earlier post, just consider that overclocking may mean not just overclocking the CPU, but also changing the frequency of the north and southbridge, the Ram (leaving it vulnerable for errors due to the clocking of the chips), the PCIe slots, changing the power consumption, temperature of chips, etcetera.
If you are a dedicated tweaker, go ahead, but for most of us here, it is highly unadvisable.
Harm Millaard