If you open the users guide it says that the green button with a black circle indicates "no performance increase" where as the green button with a red circle indicates "full performance". My understanding of "full performance" means that is will keep all the cpu's cores at full speed and not slow them down to save power. I don't have a system to check it on at the moment but pretty sure this is what it does. Open cpu-z and watch your cpu speed before and after you enable it or disable it to check. If you already have power management disabled in the bios the AMD overdrive green button shouldn't make a difference if I am correct.