the clock signal is provided for syncronization adn for correct data processing…. (try clear you DE concepts)
every ckt got limition for it maximum clock i/p…(what will happen to you if you will be forcfully over diet??)… don’t worry nothing will happen to you ic when it will be over locked. simply it will work for its maximum allowable clock freq.??.. the masimum limits are decided by the manuf. refer to the particular component data sheet for more details…