I just bought 480 Sapphire... Put it to work with 155 mh/s without mess with anything other than just to install only drivers... When i heard about Watman utility i decided to try if i can overclock the card and made another instalation just to add AMD control panel with Watman in it... Since then max hashrate i gain was 147 mh/s before driver crash... So i uninstall whole driver and software with Driver Fusion and reinstalled it again with tick only on drivers... Now it work again with 155 mh/s...
So you can concired that when you install drivers... Driver i use is 16.8.1 !