Vaio stamina-Speed swtich issue :(

I've upgraded from Windows 7 to 8 on my Vaio VPCSB series laptop ; all my programs and settings are restored but the Stamina-Speed switch does not work. PC only can detect onboard VGA , I've deleted old ATi drivers with Driver Swpeer and Installed Windows 8 drivers but no luck so far... Any suggestions?

I have the same issue on my VPCSB190X as well. I'm running with a AMD Radeon 6470M.