Windows 7, UEFI vs BIOS, GPT vs MBR notes

I’ve been digging and experimenting quite a bit with the boot processes in Windows 7 (64-bit only), trying to accomplish completely unsupported things.

Here’s a couple things I have learned that you might find helpful

  • 32-bit Windows cannot boot uefi, nor can it be booted from a (microsoft) efi bootloader. This includes Thin PC.
  • The actual windows partition and installation doesn’t seem to care how it is booted – and it doesn’t matter how it was installed:
    • For UEFI, \Windows\system32\winload.efi is used to boot
    • For BIOS, \Windows\system32\winload.exe is used instead
    • Both sets of files exist regardless the type of system windows is installed on, and can be used interchangeably – I have taken a windows folder installed on a UEFI machine and booted in on a BIOS machine, and vice versa
  • Windows Image Backups are always MBR, even if the source drive was GPT. (at least for the partition containing windows)
  • Windows Image Backup’s recovery tool will not allow you to restore from a UEFI machine to a BIOS machine but…
  • Because the image is MBR, you can boot it on a BIOS machine with a little work

Uninstalling Windows 8 when using UEFI

So you went ahead and dual booted the Windows 8 Developer Preview with your Windows 7 machine, but decided you don’t want it anymore. There are lots of instructions online for how to remove it when you are using a standard boot, but if you are using UEFI your life is much simpler. (I’m not going into detail since if you figured out how to dual boot, you probably can handle a partition or two)

Using Disk Management, delete the volume for your windows 8 installation. Optionally, expand the volume for your Windows 7 install to get the space back.

If you want to speed up the boot process a bit, Open the Advanced System Settings (rt click Computer, Properties, Advanced System Settings), click Settings… under Startup and recovery, and make sure the check box next to “Time to display list of operating systems” is unchecked, (and that Windows 7 is the default operating system).


All done! No need to edit the BCD when using EFI boot, it appears that windows automatically removes the windows 8 entry when you delete the partition. (I ran bcdedit just to check)