Overclocking a processor means enabling it to operate above the manufacturer's specified frequency.
There are definite risks that you are taking when you decide to overclock your system processor.
Many Internet sites provide instructions for overclocking. However, processor manufacturers and many computer experts believe the slight gain in performance isn’t worth the risk.

Here are some possible risks you can expect when you overclock your processor. These apply to rising the clock speed of the processor only, not changing the system bus speed above its nominal rating.

-It is possible to totally destroy a processor by attempting to overclock it. The processor will not boot at the higher speed, and when returned to its normal speed, will continue to not function. This sort of permanent failure is very rare, but it does happen. It is made more likely by using inadequate cooling.

-The processor may not work at the new speed, but may work fine when returned to its original speed.

-The processor may boot at the new speed, but you may see the system behave strangely. Random hard lockups, parity errors, resource conflicts, strange hard disk problems, beeping, application crashes, etc.

-Expect a shorter life for an overclocked processor.

-Overclocking an Intel processor explicitly voids the warranty. Other manufacturers have similar exclusions.

-Some processors normally run closer to their maximum possible speeds than others and are therefore unsuitable for overclocking.

-Excessive heat generated by an overclocked processor may damage or destroy other components inside your computer.

-It is very possible to lose data as a result of overclocking. If the processor is not functioning properly, you risk potentially damaging the structures of your hard disk's file system.

-When the processor is run at a speed that is higher than it is supposed to be run at, there is a chance that the internal components in the processor may break down over time. It is possible that when the processor is stressed by running at a high frequency, along with the extra heat, the actual metal lines inside the processor may form shorts or opens and damage the processor over a period of time.

written by Cristian L.