every Stick of RAM (even same make and model) will have different OC potential. So your limited by your slowest stick and it makes it tough to say, "use this voltage at these clocks with this CL rating." It is kind of a trial an error kind of thing. I would bump the frequency first and see if it is stable...Then i would try bumping the voltage a hair if it is stable followed by loosening the CL rating (ie going from cl 16-18-18-38 to cl 17-19-19-39 for example). It is a bit of a balancing act. Find what is stable by testing with memtest86 to verify the frequencies stability.