ASRock's auto OC'ing on the P67 Extreme6 is excellent with my 2500K. I achieved a 4.8 GHz OC, a 4.6, 4.4, 4.2 & 4.0 with the auto settings. The voltage stayed under 1.36 on all of these OC settings.
I have downclocked my system to base settings on both the CPU and GPU because the wear on the system with OC'ing. None of the games I play, nor any of the other apps need a OC to perform well, so why place additional stress on the components when it is merely for bragging rights?
When I played with manual OC'ing I found, like this article, that there was only a marginal gain from auto settings. Plus ther is the additional risk of screwing the pooch entirely and bricking the CPU or mobo by overvolting.
Unless you are a real pro and are not risk adverse, I'd recommend that you stick with auto OC'ing, and for this, ASRock has proven to be the best.