Hi, I am reading this post with a lot of attention. Regarding this post, windows 7 efi boot is only supported on a full gpt harddrive with no other partition on it. http://www.insanelymac.com/forum/index.php?showtopic=184349#2 From what I read, you need oscdimg.exe in order to boot efi mode. Have you ever gave a try to this solution ? In efi loaded windows, do you have full access to both discret and dedicated gpu on windows ?