Regardless, 4.5 is great and more than enough for gaming any day of the week. The difference between 4.5 and 4.8 might not even net you any fps gains in certain games. Depending if its CPU dependant or not.
But Sal you are correct, this is why I tend to stay away from auto OC. The voltages are preset to be safe. Asus says their implementation is actually measuring voltages to set it correctly but I highly doubt it. It probably still uses a predifined table.
Ya so start turning down the voltage and see if you can pass prime95 stress for a few hours or even a day if your really paranoid.