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Full Guide to Dual-Boot Windows 7 and 8 no Matter Which Is Pre-installed

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    It is possible to install more than one operating system on the same machine, and we call this dual boot or multiple boot. Experienced users should have little or even no difficulties in doing this, but there are a part of people who have been or are being troubled by some problems during installation process. Therefore, in this post we will show users some tips and corresponding solutions to dual boot errors.

    Currently, as Windows 7 and Windows 8 are most widely used, the question how to dual boot Windows 7 and Windows 8 is asked much more frequently. So here we take dual booting Win7 and Win8 for example.

    Dual Boot Windows 7 with Windows 8 Pre-installed

    As we know, most computers especially laptops are pre-installed with Windows 8 since the release of this new system. However, though Windows 8 brings amazing user experience and can improve computer performance, many users still like using the classical Windows 7. Therefore, some of them hope to run Windows 7 and Windows 8 on the same machine. Well then, how to dual boot Windows 7 when Windows 8 has been pre-installed?

    If your computer is configured with more than one hard disk, we highly suggest installing different Windows operating systems on different hard disks, for they bring no influence to each other and can simplify system management. To be specific, if Windows 8 has been installed on disk 0, we had better install Windows 7 on disk 1 or another disk. However, if there is only one hard disk, install different OS in different partition. If not, the later installed system will overwrite the former one, thus making the pre-installed system unbootable.

    Of course, to install a system on either different disks or the same disk, we should create a partition for this system at first. If you have created such a partition, please skip to installation directly. If not, see the following content.

    Steps to Make a Partition for Windows 7

    Right click “Computer” icon on the desktop, choose “Manage”, and select “Disk Management” to get the window below:

    make partition for windows 7

    Here I only have 1 hard disk, namely disk 0, and it is initialized to GPT. To see partition style (MBR or GPT) of the disk, please right click the disk, choose “Properties”, and tap on “Volume”. I need to shrink an existing partition on disk 0 to create an unallocated space:
    Right click a partition like partition C and choose “Shrink Volume” feature from the popup menu; then, type the value in MB to decide how much space we want to shrink from this partition.

    shrink volume

    Tip: hard disk space 32 bit Windows 7 requires is 16GB while the 64 bit version asks 20GB, but the actual value should be larger to keep smooth running if your hard disk has enough space. Therefore, we can shrink 25GB=25600MB space to create Windows 7 partition and click “Shrink” to get an unallocated space.

    Next, right click the unallocated space, choose “New Simple Volume”, and set properties like partition size, drive letter, file system, cluster size, etc. for this the newly created partition. Tip: we can label it with Windows 7 to make it easier to recognize this partition during installation.

    label volume

    When the partition for Windows 7 has been created, we need to disable Fast Startup feature of Windows 8.

    Why and How to Disable Fast Startup

    If Fast Startup feature is enabled, chkdsk will be running when we are installing Windows 7. As a result, we may no longer see the dual boot menu the next time we turn on our computer. Detailed steps to shut down it are as follows:
    Go to Control Panel, select View by: Small Icons, choose Power Options, select Choose what the power button does, uncheck Turn on fast startup, and click Save changes.

    turn off fast startup feature

    After these steps, we can shut down computer to install Windows 7 if we have had Windows 7 installation disk, like CD, DVD and USB flash drive.

    Tip: if you are planning to install Windows 7 from USB flash drive, the drive should be formatted with FAT32, because UEFI firmware does not recognize NTFS. If you want to install Windows 7 from hard disk, you also need to create a FAT32 partition to save Windows 7 installation files, and the reason is same. Moreover, installing Windows 7 from hard disk or USB flash drive in UEFI mode requires downloading the BOOTX64.EFI file to get UEFI boot support. Of course, you can also get it from the installation files of Windows 8, but it is called Bootmgfw.efi in this system. You need to copy the file, then rename it to BOOTX64.EFI, and finally save it to \EFI\Boot\ of Windows 7 installation files. If there is no folder named Boot, create one.

    How to Install Windows 7 on Windows 8

    As we know, most computers with Windows 8 pre-installed support both UEFI BIOS and Legacy BIOS, but Windows boots via UEFI mode by default. To see whether UEFI BIOS is supported or Legacy BIOS is enabled, please enter BIOS. Detailed steps are: start computer and then press a key like F2, Esc, and Delete before Windows is loaded. If you do not know which key to press, try searching how to enter BIOS plus your BIOS type or computer trademark on the internet. I press F2 to enter the BIOS setting:

    items under boot menu in BIOS

    Under the Boot menu we can see clearly that my computer is configured with UEFI boot, but Legacy Boot Option Rom is disabled. Under this situation, we can only install 64 bit Windows 7 on a GPT disk. Why? According to Microsoft, we know booting from GPT disk must be under UEFI mode, but UEFI firmware does not support 32 bit system. Therefore, 32 bit Windows 7 cannot be installed to a GPT disk. Of course, when Legacy BIOS is supported, 32 bit Windows 7 can be installed to a MBR disk. Some mainboards can either support UEFI BIOS and Legacy BIOS:

    motherboard supporting uefi and legacy

    Then make corresponding changes in BIOS:
    1.Disable OS Optimized Defaults if there is such an option. Enabling it will restore all settings to the state when Windows 8 is installed. Under this state only Windows 8 can be installed.

    disable os optimized defaults

    2.Disable Secure Boot. It is a feature specially designed to defense virus or malware. Motherboards configured with secure boot are built with some public keys. Only programs or systems that have been signed by these public keys can be loaded. Most of the time, Windows 7 hasn’t been signed. As a result, it cannot be loaded if secure boot is enabled.

    disable secure boot in BIOS

    3.If you are going to install Windows 7 (both 32 bit and 64 bit) to a MBR disk, please enable Legacy BIOS in boot mode, which has been introduced.

    4.Set boot priority order. If you want to install Windows from CD or DVD, make CD-ROM as the first boot device. If installing from USB flash drive, make removable device as the first boot device. Under different types of motherboards, we should perform different operations. And you can get specified steps from the internet. Here, we just make Phoenix SecureCore Tiano for example: disable Secure Boot, enable Load Legacy Option Rom, and make CD/DVD drive or Removable Drive as the first boot device.

    set boot order

    After all changes are made, we can press on F10 to save changes and quit from BIOS. At this time, if the installation disc has been connected, Windows 7 will start installing. If not, insert the disc and restart computer.

    Once the computer starts from CD or DVD, we may get the following message:

    press any key to boot from CD or DVD

    Please press any key to boot from installation disc.

    install Windows 7 startup interface

    Then, choose a language and click “Next”.

    click installation now

    In this step please click “Install now” button. Then, accept license terms, select custom installation, and then choose a partition or drive to install Windows 7 to. However, during this step you may receive the following error:

    cannot install windows on MBR disk

    That is because Windows can only be installed to GPT disk under UEFI mode but you plan to install Windows 7 on a MBR disk, which has been introduced just now. At this time, the best solution is to convert the target disk to GPT. If there is no important data saved on this disk, we can delete all existing partitions and then initialize the disk to GPT by calling out Diskpart. Steps are as follows:
    Press on Shift + F10 key to launch CMD and then type Diskpart; then, type the following commands successively: type list disk and press Enter, type select disk N (N is the number of the MBR disk) and press Enter, type clean and press Enter, type convert gpt and press Enter, and finally type exit to quit from diskpart.

    However, if the MBR disk saves files we want, please stop Windows 7 installation, then boot Windows 8, and convert MBR disk to GPT by using MiniTool Partition Wizard, because this program can help complete the conversion without deleting any data and partition. After the converting is completed, we can install 64 bit Windows 7 on Windows 8 computer like installing any other Windows operating system.

    Once the partition that will install Windows 7 has been decided, Windows will start installing automatically. It may restart for several times, so please wait patiently.

    However, after installing Windows 7 we may find the original Windows 8 cannot start normally especially when they are installed on the same hard disk, and the largest reason may be that boot files of Windows 7 overwrite those of Windows 8. Microsoft has given such a warning in its official website:

    You must install the older operating system first, and then install the more recent operating system. If you don't (for example, if you install Windows Vista on a computer already running Windows 7), you can render your system inoperable. This can happen because earlier versions of Windows don't recognize the startup files used in more recent versions of Windows and can overwrite them.

    At this time, repairing startup files via the Windows 7 or Windows 8 installation disc may fix the error.

    How to Fix Startup Files When Windows 8 Cannot Boot

    In the Install now interface please choose “Repair you computer” rather than installing Windows:

    repair computer in windows installation disc

    Then choose Startup Repair.



    Next, choose a Windows OS to repair. You may need to do startup repairing for several times, so please wait patiently. After the repair is done, Windows 8 may be bootable.

    Now 64 bit Windows 7 has been installed. Next, let’s see how to dual boot Windows 8 when Windows 7 has been installed since many people want to experience amazing features of this new operating system.

    Dual Boot Windows 8 with Windows 7 Pre-installed

    First of all, we also need to check the version of Windows 8, the partition style (MBR or GPT), and boot mode. If the Windows 7 computer uses UEFI mode only, we can only install 64 bit Windows 8. If the Windows 7 computer employs Legacy boot mode only, we cannot install Windows 8 to a GPT disk, but there is a solution, and it is to convert GPT disk to MBR disk. For lossless converting, you can also turn to MiniTool Partition Wizard. If both Legacy BIOS and UEFI BIOS are supported, we are able to install Windows 8 to a MBR disk or install 64 bit Windows 8 on a GPT disk.

    Then, create a partition for Windows 8 by taking the same way as that to make a partition for Windows 7.

    Tip: if you want to install Windows 8 on a different MBR hard disk, this disk should be unallocated or should have 1 primary partition at least. If not, you will fail to install Windows, because boot files of Windows should be saved to the partition which can be set active, and only primary partition can be set active. For details, please see Accidentally Marked Drive C Active. If there are logical partitions only, convert one of them to primary, and MiniTool Partition Wizard can help you do it without losing any data.

    Next, install Windows 8 like installing any other Windows OS.

    However, if Windows 7 and Windows 8 are installed on two different MBR disks, we should set boot order in BIOS the next time we are planning to start Windows 8, namely making the disk saving Windows 8 as the first boot device. If not, Windows 7 will be loaded by default. But for Windows booting via UEFI + GPT, there is no need to do this, because UEFI firmware provides a boot manager which allows you to choose which OS to start.

    Do you think this post is useful for dual booting Windows 7 and Windows 8?