Windows - Dual Boot on a HDD (GPT partition)

October 2016

You want to make a DUAL BOOT (Windows 8 and Windows 7 - 64 bit) on your hard drive without having to erase your current data, this can be achieved ona computer with a UEFI motherboard and hard drive in the GPT format:


  • To begin, disable the secure boot feature in the BIOS of your motherboard and enable BIOS legacy mode.
  • You will then need to change the UEFI boot order, putting the CD/DVD ATAPI drive first.

Create a partition

  • Right click on your "My Computer" and select "Manage".
  • A new window should appear. In the Disk Manager search for "Disk 0" and select the partition you want to divide (normally the one on which your current OS is installed)
  • Right-click > Shrink.
  • Select the size of your new partition.
  • Your new partition will appear as unallocated space.
  • Right-click the partition and select "New Simple Volume", which should bring up a new wizard to create a simple volume.
  • Choose a drive letter (G:, H:, etc ...) and follow the onscreen procedure to finalize the creation of your new partition.

The commands to be entered

Open the command prompt (Run > type "cmd") and run the following commands:
  • Type "DISKPART" and confirm with Enter.
  • DISKPART should then open, type "SELECT DISK 0" a and confirm with Enter.
  • A message stating that disk 0 is selected should be displayed.
  • Now type DETAIL DISK and press enter: The volumes present will be listed.
  • Then locate the volume that you created earlier and enter "SELECT VOLUME volume_number" and press Enter.
  • DISKPART would then indicate that the volume has been selected.
  • Type AUTOMOUNT and press Enter
  • DISKPART will then tell you that the automatic mounting of new volumes enabled.
  • Finally you need to type EXIT to exit DISKPART and close the CMD window.
  • Now you should be ready to install a new operating system.

Installing the new OS

Note that: you must use the 64-bit versions of Windows for GPT formatted drives
Simply insert the installation DVD of Windows 7 and run from the desktop. During installation, you must choose the volume that you have created earlier.

Thanks to toto13015 for this tutorial.

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