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Install Dual-Boot of Windows 7 and Windows 8 on a Windows 8 computer (Win8 installed first)

Last reviewed: July 2013

Introduction

This guide shows how to correctly and safely create a natural dual-boot of Windows 8 and Windows 7 on a computer with Windows 8 already installed. You can then run either of those two Windows by selecting one from a menu during bootup. No data loss will occur and a third-party boot utility is not used.

In this procedure you need to resize the Windows 8 drive to make room for Windows 7 unless you happen to have sufficient free disk space or you install Windows 7 on a second hard disk. This example uses a single hard disk.

A 64-bit Windows 8.1 was used in testing and a 64-bit Windows 7 was added (it can be a 32-bit Windows 7 if you are have the MBR, and not GPT/UEFI, system). Read How to Check if your hard disk drive is using GPT or MBR. The computer used was a 64-bit Dell Studio XPS 8100 (2.93 GHz), Core i7, 8 GB RAM DDR3, NVidia GeForce GTX 460, 1 TB SATA hard disk (not using GPT/UEFI).

The procedure used is quite easy and suitable for most users.


Important Installation Notes

Full Installation CD/DVDs. The Windows you are adding cannot be installed from a Recovery partition or Repair CD/DVDs provided by some OEMs. You need the full installation or setup version to install a Windows.

Shrinking a Windows 8, 7 or Vista drive. You should use Shrink in Windows' Disk Management to resize the Windows partition. You can read Shrink the Windows 7 or Vista Partition for instructions on completing this task successfully. Use the free GParted Live CD to gain disk space only if you must - read the page Use GParted to Resize the Windows 8, 7 or Vista Partition to learn how.


SUMMARY of Procedure (Advanced users)

  1. Backup important data.
  2. Create Unallocated or RAW space for Windows 7 at end of the hard disk (use Shrink) or use a second disk.
  3. Turn off Fast Startup in Power Options in Windows 8.
  4. Bootup from Windows 7 DVD, select Install, then Custom, and install Windows 7 on the new Unallocated space.
  5. Fix the Restore Points problem in Windows 7.
  6. Test effect of turning on Fast Startup in Power Options in Windows 8.
  7. Optional: Use bcdboot c:\windows in an elevated Command Prompt in Windows 8 to restore the GUI boot menu.

That's it! The Windows boot loader menu now allows booting to Windows 8 and Windows 7.

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Details: Create a Dual-boot with Windows 7 when Windows 8 is already installed

Installing other operating systems on your Windows 8 computer may invalidate your warrantee.
It's important to follow the instructions exactly as stated and you should start with a properly working Windows.


Make your preparations

  1. Make sure you can boot from a bootable CD/DVD
  2. Backup important data before making any changes to a partition. You can burn files to a CD, clone an image of your hard disk, copy files to a USB flash/pen/thumb drive, or use an USB external drive (a good choice)
  3. Disconnect all unnecessary external devices before you start.

Make free space for Windows 7

The Windows 8 drive is resized using Shrink in Windows' Disk Management leaving Unallocated space at the end of the disk (to the right). You can create a new custom-sized partition (RAW) in Unallocated but do not Format it.

Always note the size of each partition and also label each (this guide will use wn_8 and wn_7).
You can use a second hard disk for Windows 8 but it should use the new GPT Partition Table if the first disk uses GPT.

  1. Restart computer correctly (close all programs before you Restart computer).
  2. Open Disk Management in Windows 8 (press Win and X keys, click Disk Management).
    • Optional: Right-click your CD/DVD drive(s), select Change drive letter and paths..., and click Change.
      - change the drive letter to K (get it out of the way!).
    • Right-click the Windows 8 Volume (probably C:), and select Properties.
      In the General tab, enter wn_8 as the label for the Windows 8 volume, and click Apply.
  3. Still in Disk Management in Windows 8
    • Right-click the wn_8 volume, and click Shrink Volume.
      • In Enter the amount of space to shrink in MB:, enter enough windows 7.
      • Click the Shrink button (it may take some time!).
        Note that we will leave the newly acquired free space as Unallocated (preferred) or RAW.
      If Shrink does not give you sufficient Unallocated space, read how to Shrink the Windows 8, 7 or Windows Vista Partition for instructions or use the free GParted Live CD. Then return here.
  4. Restart to Windows 8.
    • Open Disk Management and check that the change made is correct.

Disable Fast Startup in Windows 8

It's been claimed that failing to disable Fast Startup in Windows 8 can result in Check Disk running when installing Windows 7. Also the dual-boot menu may not appear, and Check Disk may run every time you boot to Windows 7 when it's on a second hard disk. THPC has not experienced this during testing and it may be system dependant. However Fast Startup has only a small effect so let's play safe and disable it!

How to turn off Fast Startup in Windows 8

  1. Press Win + X keys and select Power Options
  2. Click Choose what the power buttons do
  3. Click Change settings that are currently unavailable
  4. Uncheck Turn on fast start-up (recommended) and click the Save changes button.

Now Install Windows 7 when Windows 8 was Installed first

Traditionally, installing an older Windows on a computer containing a newer version stopped that newer Windows from booting. This was caused by different versions of the boot loader. The new boot loader used in Windows 8, 7 and Vista is much friendlier!

  • Bootup from the Windows 7 installation DVD.
    • Select your Language, and Time..., and click Install now.
    • In Which type of installation do you want? select Custom (Advanced).
    • In Where do you want to install Windows? select the Unallocated area prepared earlier.
  • Restart your computer when installation is complete. Select Windows 7.
    (Windows 7 has been automatically added to the boot menu which still contains Windows 8. Nice!)

    In Windows Explorer, label the Windows 7 drive to wn_7 (right-click the Win7 drive and select Properties).
    Sometimes the Windows 8 partition has no drive letter in Windows 7. You can assign one Disk Management.

    You may now be able to turn on Fast Startup without ill effect - turn it off again if Check Disk is problematic.

Congratulations! You've created a natural dual-boot of Windows 8 and Windows 7 when Windows 8 was installed first.

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Fix Restore Points Problem in Windows 7 (advanced users)

Every time Windows 7 is booted, it destroys Windows 8's Restore Points and all except the most recent backup files from Complete PC Backup - read Microsoft's Knowledge Base article 926185.

A small addition to Win7's registry avoids this problem by making the Windows 8 partition inaccessible when, and only when, Win7 is running. You must, however, use extreme care to ensure you enter the correct drive letter in the following corrective procedure. You must never enter the drive letter used by Win7 - that would prevent Win7 from ever starting again! This fix is applied when Win7 is booted and not from any other Windows.

  1. Download this tiny xp_rstr_fix.reg file, xp_rstr_fix.zip, and unzip it to Win7's Desktop.
  2. Startup to Windows 7 . It must be Win7 and not any other version of Windows.
  3. Note the drive letter allocated to the Win8 partition in Windows Explorer (it's normally C).
  4. Right-click xp_rstr_fix.reg on the Desktop and select Edit. Look at this line in xp_rstr_fix:
    "\\DosDevices\\Z:"=dword:00000001
    • Carefully change that Z to the drive letter allocated to the Win8 partition
      (make sure you do not remove the \\ before the letter or the : after the letter).
    • Save the file back to the Desktop as xp_rstr_fix2.reg
    • Right-click the new xp_rstr_fix2.reg on the Desktop, click Merge, and click OK.
  5. Reboot to Win8, and create a new Restore Point (right-click Computer > Properties > System Protection).
  6. Delete the .reg files on Win7's Desktop when you're finished.

When Win7 is booted the Win8 drive will still be allocated a drive letter. However you will be denied access to the contents of the Win8 drive and the drive will appear to be unformatted (RAW) even though the contents have not been changed. When you boot to Win8 you will have access to all your drives including the Windows 7 drive.

This is the full xp_rstr_fix.reg file: (the blank line is required)

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices\Offline]
"\\DosDevices\\Z:"=dword:00000001

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Repair Windows 8 Boot Menu and Startup

Users will have noticed that the above creates a plain boot menu. This is perfectly fine but some would prefer the Win8 graphical menu which also has additional options. This simple procedure will return that graphical boot menu:

  1. Boot to Windows 8.
  2. Hold down both the Win and X keys and then press the A key (to open an elevated Command Prompt).
  3. Run this command at the prompt:
    bcdboot c:\windows
    where C is the letter allocated to your Windows 8 (change the C if necessary).
  4. Reboot. The Windows 8 GUI boot menu is back!

Windows 8 is the default boot. You can alter this in Change defaults or change other options on the GUI menu.


If you ever need to do a fuller repair of the Windows 8 startup, you should do the following:

  1. Bootup from your Windows 8 DVD to the first screen ("Windows Setup").
  2. Hold down the Shift key and tap F10 (to open a Command Prompt).
    Type in these commands and press Entry after each (note the space after each BOOTREC):
    bootrec /fixmbr    - to update the Master Boot Record - just in case!
    bootrec /fixboot    - to recreate the Win8 Boot Sector of the system partition
    bootrec /rebuildbcd    - to rebuild the BCD data & boot menu or just add a compatible Windows to the menu
    exit
  3. Exit the installation now and reboot.

Note: The Bootrec command has not been tested on the newer (U)EFI / GPT systems.


If you ever want to switch back to the Windows 7 boot menu, you can do this with ease by using the free EasyBCD.

The EasyBCD utility allows users to make changes to the BCD in a simple graphical manner. Running it will automatically convert the Windows 8 startup to one for Windows 7 including its boot menu. You can set Windows 7 as the Default boot in the Edit Boot Menu section of EasyBCD. At that stage you will basically have a Windows 7 computer that still allows you to boot to Windows 8 - unless you decide to remove Windows 8!

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Please remember that you alone are responsible for the consequences of any changes you make to your computer hardware or software.

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