RAM is probably the most finicky component. They should overclock at least somewhat when you increase the voltage but Sandy Bridge prefers 1.5v or less most of the time and you may have a bad kit. What is this system going to be used for? most work doesn't have any improvement from getting RAM faster than 1600 and even then it isn't much better than 1333. Games don't take advantage of faster RAM at all and the only thing I know to be sped up considerably is compression.