Dual Boot Windows 10 with Windows 7 or 8

Considering a Windows 10 Installation? Dual-Boot is Recommended.

Installing Windows 10 directly onto your main computer isn't generally advised. However, should you choose to proceed, establishing a dual-boot configuration is a prudent step. This allows you to select which Windows version to launch upon system startup.

Prior to initiating the installation process, ensure comprehensive backups of all critical data are created. While data loss is unlikely when following the correct procedures, unforeseen errors or bugs could potentially result in file corruption or loss. Taking preventative measures is always advisable.

Initial Installation Considerations

Important Note: Previously, a Windows 10 upgrade was often a prerequisite before a clean installation could be performed. This stemmed from complexities within Microsoft’s licensing system, even when a free version was available.

Current Installation Procedures (2019 and Beyond)

As of 2019, Windows 10 has reached a stable state. The initial upgrade step is no longer required.

A clean installation of Windows 10 can still be achieved without prior upgrades. Providing a valid Windows 7 or Windows 8 product key during the installation process will typically allow you to activate Windows 10 at no additional cost.

Here's a summary of key points to remember:

Backups are essential before any major operating system change.
A dual-boot setup provides a safety net and flexibility.
The upgrade requirement has been removed for clean installs.
A Windows 7 or 8 key can often activate a free Windows 10 installation.

Adjusting Partition Size for Windows 7 or 8 to Accommodate Windows 10

Related: Windows 10 is Now Available: Considerations for Upgrading?

Prior to installing Windows 10, sufficient disk space must be allocated. If your computer features multiple hard drives, with at least one being unoccupied, this step can be bypassed. However, a common scenario involves installing Windows 10 alongside your existing Windows 7 or 8 installation on the same drive.

The Disk Management utility is utilized for this purpose, regardless of whether you are running Windows 7 or Windows 8. Initiate the utility by pressing the Windows key + R, then entering diskmgmt.msc into the Run dialog box, and finally pressing Enter.

Identify your system partition, typically designated as the C: drive. A right-click on this partition will reveal a context menu; select "Shrink Volume" from the options. Alternatively, if your hard drive contains multiple partitions, you can opt to resize a different partition to create the necessary free space.

Specify the amount by which to shrink the volume, ensuring enough space is freed for the Windows 10 installation. Microsoft indicates that Windows 10 shares the same system requirements as Windows 8. The 64-bit version of Windows 8.1 necessitates a minimum of 20 GB of hard drive space; however, allocating more is generally recommended.

Once the partition has been successfully shrunk, the installation process can proceed.

Acquiring Windows 10 and Initiating the Installation Process

Obtain a Windows 10 ISO file, and subsequently create either a bootable DVD or a USB flash drive from it. Utilizing Microsoft’s Windows USB/DVD Download Tool remains a viable option, enabling the imaging of a Windows 10 ISO file onto a USB drive.

Ensure the DVD or USB drive remains connected to your computer and proceed with a reboot. The system should then initiate the Windows 10 installer automatically. Should this not occur, adjustments to the boot sequence within the BIOS settings may be necessary.

Computers running Windows 8, equipped with the more recent UEFI firmware, will require the use of Windows 8’s advanced startup options to select the USB drive or DVD drive during the boot process.

Boot Order Considerations

The boot order determines the sequence in which your computer attempts to start from different devices. Adjusting this in the BIOS ensures the installer media is prioritized.

For UEFI systems, accessing the advanced boot menu provides a direct method for selecting the installation source without altering the permanent boot order.

Related: Understanding the Differences Between UEFI and Traditional BIOS

Installing Windows 10 Alongside Windows 7 or 8

Begin the Windows 10 installation as you normally would. First, choose your preferred language and keyboard layout. Then, proceed by selecting "Install now."

After accepting the license terms, opt for the "Custom: Install Windows only (advanced)" installation type. Choosing to upgrade would result in an update of your current Windows 7 or 8 installation to the Windows 10 Technical Preview. The custom installation allows for a parallel installation of Windows 10.

You will then be directed to the screen for selecting the installation location, which manages disk partitioning. Provided you previously adjusted the size of your existing Windows partition to create free space, you should see an "Unallocated Space" option. Select this unallocated space and click "New" to define a new partition within the available area.

A dialog box requesting the desired partition size will appear. The default setting allocates all remaining unallocated space. Simply click "Apply" to create the new partition utilizing the full available space.

The Windows installation program will automatically create the new partition and select it for use. Proceed with the installation of Windows 10 onto this newly created partition by clicking "Next."

The remainder of the Windows installation process will complete automatically, without requiring further input from you.

Selecting Between Windows 10, 7, or 8

Upon system startup, a choice between Windows 10 and either Windows 7 or 8 will now be presented to you. Switching between these operating systems is accomplished by restarting the computer and then selecting the preferred Windows version from the boot menu.

The "Change defaults or choose other options" link on the screen allows for customization of these settings. This feature enables you to designate a default Windows operating system and adjust the duration for which the operating system selection screen is displayed before the default version automatically loads.

Both Windows versions utilize the NTFS file system, facilitating seamless file access regardless of the currently running operating system. The other Windows installation will appear as a separate drive with its own assigned drive letter within File Explorer or Windows Explorer.

To improve organization, you can right-click on a drive and choose "Rename" to assign a more informative label, such as "Windows 10" or "Windows 7."

When establishing a dual-boot system with Windows 10 and Linux, it is recommended to install Windows 10 first, followed by the desired Linux distribution. This approach ensures optimal configuration, as Linux will install the GRUB2 boot loader.

The GRUB2 boot loader will then provide a menu allowing you to select either Linux or Windows at startup. Installing Windows 10 after Linux may result in its boot loader overwriting the Linux system, necessitating a restoration of the GRUB2 boot loader.