Depends on the amount of voltage you can give your hardware. Generally, CPU voltage isn't a factor and a .6Ghz overclock should be possible with better than stock cooling and a slight increase in voltage. Say like 1.5v or something, up from 1.4v default.
You RAM however, if you want to overclock that then you will most likely need to give it more voltage.
Or you could totally ignore tha RAM like I do and simply overclock the CPU but that would result in a less-than-ideal overclock.