Translations:GRUB/162/en

An already installed Windows will refuse to boot when the boot mode or the partitioning scheme is changed. Also, older Windows systems don't support GPT (or EFI) at all, demanding that a BIOS or the EFI-CSM along with an MBR must be used. If Windows supports EFI it can be re-installed in the native UEFI mode and the GPT partitioning scheme, as well as Linux; see section UEFI with GPT.