dun no which clocking u asking...
In digital circuitry, clocking is a way to ensure that data signal is sampled at the intended interval to prevent 'misreading the signal'. It also allows electronic logical device to anticipate delays and data sychronisation.
clocking is normally rated in Hertz(Hz), 1 Hz means the device perform 1 cycle of processing per second. Therefore the higher the Hz the faster the device can process information.
However there is always a limit to how fast the device can be clocked. It can be analogical to a pail fitted with a faucet. How fast can you fill up the pail is dependent on the size of the pail and water source, and the speed to empty the pail is dependent on the size of the pail and the size of the faucet.
By clocking higher than the device rating, there is no assurance that the signal will be ready to transact which may lead to erroneous data and also cause the device to dissipation higher amount of heat.
wiki :
http://en.wikipedia.org/wiki/Clocking