Hi,
I install Windows 8 in EFI mode on my iMac with Ati Radeon Mobility 4850. Everything works fine with the "Default Generic VGA Adapter" but black screen appears with the ATI drivers for Win8 WDDM 1.1 It seems that graphic acceleration part does not work in EFI mode BUT it works in BIOS mode.
Does AMD/ATI drivers handle EFI mode now or in the future ?
Thanks for your attention.