The problem that there is a wall when it comes to the base clock and even when you get passed that the gpu becomes the limiting factor in overclocking with it's power consumption. The cpu by its self can crack 4ghz very easily and if the sample is a good bin it can go higher still. Since most of the bins are not as great as people thought or wished for most don't even get passed 3.6ghz and the few good low volt low amp bins end up in laptops that could have gone close to 5ghz with the unlocked multiplier only hit 3ghz in overclocking in laptops. In short there is a glass ceiling that will always be there to hold everyone back. The only way to push it higher is to keep it at ever lower temps and make sure the board can handle the power consumption.