it is possible since heat is the number one enemy to overclocking. but it is not the only enemy. other things like not enough voltage to sustain the extra speed (ie bit like needing more fuel/air mixture in an engine to make it go faster) , transistor cross talk (usualy due to the quality of the fabrication) and current leakage, will all limit the core to its maximum overclock
on the memory, just look at your chips, you should be able to find a number telling you the response time. ie if u have a 4nano second ram chip then in theory that chip is capable of 250Mhz. this speed is also down to things like voltage, heat, etc
so u can cool all you want but at some point no amount of cooling is going to help u go faster