Multiboot: Several systems in parallel on one PC

Older and newer Windows versions and Linux can be set up side by side on one PC. However, you should follow a few rules to ensure that everything runs smoothly. Multiboot tools also do a good job here.

One computer – multiple operating systems. This offers you numerous useful options and areas of application. For example, Windows 7 can continue to be used if this is required for certain applications. As a rule, however, you start a current Windows 10. With two Windows 10 versions next to each other, you can use one for safe software tests, the other serves as a stable work system. Or you can also install a Windows pre-release version (Insider Build) to try out new functions.

An additional license is not required for the second Windows. If Windows has already been activated once on the computer, another installation is activated automatically. You do not have to enter a product key.

Anyone planning to switch to Linux should first try a live system and then install Linux on the same computer as Windows. Linux can also be set up on a USB stick; you don’t have to change anything in the previous configuration.

1. Adjust the settings in the BIOS / firmware setup

Call up the BIOS / firmware setup. To do this, click the “On / Off” button in the lower right corner of the Windows logon screen, then hold down the Shift key and select “Restart”. Then go to “Troubleshoot -› Advanced Options – ›UEFI Firmware Settings” and click “Restart”. Check the boot settings. With newer PCs or notebooks, an option such as “Uefi only” can be found in a menu labeled “Boot” or “Boot Order” (or something similar), which can stay that way. However, caution is advised when “CSM”, “Launch CSM” or “Uefi and Legacy” is activated. The bios emulation CSM (Compatibility Support Module) ensures that the computer can boot in both Uefi and Bios mode.

In this case, when starting the system from the Windows or Linux installation medium, make sure that the Uefi or Bios / CSM mode is actually used, depending on the existing installation (see box).

If you want to install Linux, you should also deactivate Secure Boot. The setting for this can usually be found under a menu such as “Bios Features”, “Security” or similar. In the following, set the option to “Disabled”. Secure Boot ensures a manipulation-proof boot environment through signed files. Current Linux distributions also support this, but only with a standard installation. As soon as unsigned drivers are added, for example for the graphics card, Secure Boot prevents the system from starting.


Deactivating Secure Boot: Even if most Linux distributions support Secure Boot, you should deactivate the function. This avoids start-up problems with subsequently installed drivers.

Specify the boot order so that you can boot from the installation medium. The settings can be found in the menu “Advanced BIOS Features”, “Boot Features”, “Boot” or similar. On newer PCs there is usually a list of boot options that you can use to select the boot partition after “Boot Option # 1”. This only works if the installation system is on the USB stick and it is connected to the PC. If the PC does not boot from the installation medium, call up the settings again and adjust the boot options.

Alternatively, you can use the boot menu of the firmware, which you can usually access by pressing the Esc, F8 or F12 key (see the motherboard / notebook manual). It shows a list with all hard disks or boot managers in which you can select the one you want.


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2. Create space for another operating system

Each operating system needs its own partition. This can either be on the single hard drive / SSD in the computer or on a second hard drive / SSD.

Ideally, there is a second drive in the PC on which you can install another Windows or Linux. Systems and bootloaders can then be set up independently of one another. You are on the safe side if you temporarily disconnect the previous system hard drive and only use the hard drive on which you want to install the new system. The method also offers the advantage that the second system can be easily removed. All you have to do is reformat the hard drive and then remove any existing boot menu entries.

Shrink partition: If no empty partition is available on the hard drive, shrink the Windows partition to the desired size. This creates space for another operating system.


Shrink partition: If there is no empty partition on the hard disk, shrink the Windows partition to the desired size. This creates space for another operating system.

USB sticks or external USB hard drives can also be used for a second system. With Linux this works without any problems (see point 10). This type of installation is not intended for Windows, but it still works with some restrictions (see point 7). However, Windows offers installation on a virtual hard disk. You do not need to change anything on the existing partitions (see point 8).

If there is only one hard drive or SSD in the computer, shrink the Windows partition. The size of the partition can be changed via the disk management (Win-R, diskmgmt.msc). Before you get started, back up all your important data. Changes to the partitioning always involve a certain amount of risk. You can create a backup using

Macrium Reflect Free

In the disk management, right-click in the lower half of the window on the partition bar for the disk and select “Shrink Volume” from the menu. Now enter the required size of the new partition under “Storage space to be reduced in MB:” and click on “Reduce”. A partition of at least 32 GB is required for Windows (64-bit), for Linux 20 GB. Much more is better, otherwise space will quickly run out.

You can also use partitions on Windows

Minitool Partition Wizard

in a Linux live system or the Linux setup tool, reduce, create or change. All tools are considered reliable. However, you should always edit partitions with the same program, because there are small differences in the way they work.

3. Create a USB stick for the Windows installation

Start installation from USB stick: With Rufus you create a bootable USB stick from a Windows installation ISO for the new installation of a second system.


Start installation from USB stick: With Rufus you create a bootable USB stick from a Windows installation ISO for the new installation of a second system.

The installation media for Windows or Linux are supplied as ISO files. You can burn an installation DVD from this. However, a setup stick is better because the installation then runs faster.

You can download the ISO file of the current Windows 10 version via the Microsoft

Media Creation Tool
which can also create a bootable USB stick.

An alternative is

. Now click on the small arrow next to “Selection”, select “” and click on “”. Now select “Windows 10”, the desired version, edition, language and architecture (64-bit or 32-bit) – each time you click on “Next”. Finally click on “”.

Setup stick for Linux: Rufus can also transfer Linux bootable to a USB stick. The tool usually sets the correct settings for Linux automatically.


Setup stick for Linux: Rufus can also transfer Linux bootable to a USB stick. The tool usually sets the correct settings for Linux automatically.

Connect your USB stick to the PC and save all data on it. Enter the stick under “Drive” in Rufus. After “Start type” you select the ISO file downloaded with Rufus or you can enter a different ISO file after clicking “Select”. For “Image properties” leave “Standard Windows installation”. Under “Partition Scheme” set “GPT” and under “Target System” select “UEFI (without CSM)”. If the installation is to take place on a computer without Uefi firmware or in Bios / MBR mode, select “MBR” and “BIOS (or UEFI-CSM)”. Finally click on “Start” and follow the further instructions on the screen.

4. Create a USB stick for the Linux installation

You can create a bootable installation stick for Linux with

. Enter the desired ISO file after clicking on “Select”. Rufus adjusts the settings automatically. Then click on “Start” to transfer the files to the USB stick.

5. Install Windows 10 alongside Windows

Install Windows: In the


Install Windows: In the “Installation type” dialog, click on “Custom: Install Windows only”. Then choose an empty partition as the installation target.

Boot the computer from the Windows installation DVD or from the installation stick (see point 3). For the Uefi mode, select the entry preceded by “UEFI”. Now follow the instructions of the setup program and select the entry “User-defined: only install Windows (for advanced users)” under “Installation type”. When asked “Where do you want to install Windows?”, Enter a free partition on the first or second hard drive. Click “Next” to start the installation.

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When installing alongside another Windows on the same hard disk or on a second hard disk, the new Windows version is automatically integrated into the boot menu. Here you now select which Windows you want to start. If the hard disk with the main system was previously separated from the PC, there are several options. You can select the desired system via the BIOS boot menu or change the boot sequence in the BIOS / firmware setup to switch between the Windows versions (see point 1).

Adjust boot order: The last Windows installed appears at the top of the list and starts by default. The order can be changed via Bootice.


Adjust boot order: The most recently installed Windows appears at the top of the list and starts by default. The order can be changed via Bootice.

If this is too impractical for you, add a boot menu entry to the boot manager of the newer system. Start the newly installed Windows 10 and then the tool

. Then go to the “BCD” tab and click “Easy Mode”.

The list of systems only says “Windows 10”. To make it easier to differentiate, assign another name after “OS title:”, such as Windows 10 2004. Then click on “Save current system”.

Now click on “Add -› New Windows 7/8 / 8.1 entry ”. Select the option “Partition”, underneath the hard drive with the other Windows system and after “Partition” the Windows partition. For example, enter Windows 10 (old) after “OS title” and “de-DE” after “Language”. On the left side, select “de-DE” after “Boot language”. You can remove the check mark in front of “Metro Boot Manager (Win8)”. You start the boot menu in the old style, which enables a faster system start.

Entries in the boot menu: Add the Windows installed on the hard disk to the boot configuration on the USB stick so that both systems can be started.


Entries in the boot menu: Add the Windows installed on the hard disk to the boot configuration on the USB stick so that both systems can be started.

Click on “Save Globals” and on “Save current system”. Set the boot sequence in the BIOS so that the PC boots from the second hard drive with the new Windows 10 by default. Use the boot menu to choose between the systems.

Check the boot configuration of the PC

A typical computer with Windows 10 pre-installed boots in Uefi mode. You can check this by pressing the Win-R key combination, afterwards


Type in and confirm with “OK”. “UEFI” is written after “BIOS mode”. If the Windows installation was carried out with active BIOS emulation (CSM, Compatibility Support Module) or no Uefi firmware is available, “Previous version” is shown here.

Other operating systems must always be installed in the same mode as the existing one – i.e. Bios / CSM or Uefi. In this article we assume that Uefi is activated and Windows starts in Uefi mode. The multiboot configuration is more reliable and easier to configure. If Windows is installed in BIOS mode, the instructions apply accordingly.

7. Set up Windows 10 on a USB drive

If there is no free partition or a second hard drive, Windows can also be installed on a USB stick or a USB hard drive (Windows To Go). However, this is not intended by Microsoft and is associated with restrictions. For example, no function update is possible. To get a newer Windows 10 version, you have to reinstall the system on the USB stick. This would be too cumbersome with productively used Windows, but with a second and test system it would be manageable.

Use Rufus for the Windows To Go installation. Select the USB stick under “Drive”. Click on “Selection” and enter the desired ISO file for the installation. Under “Image Properties” set “Windows To Go” and under Partition Scheme “MBR”. Under “Target system” then select “BIOS or UEFI” and click on “Start”. If the ISO file contains several images, select the Windows edition you want, for example “Windows 10 Pro”. Click the “OK” button and confirm with “OK”.

So that the PC boots from the USB stick, change the boot sequence (see point 1). After the first start, the second phase of the Windows installation begins with the preparation of the hardware and a restart takes place. In the third phase, the setup asks you for the keyboard you are using, for example, and you create a user account. Finally, you will be taken to the Windows desktop.

There is a separate Windows boot environment on the USB stick. As described in point 6, you can integrate the system on the hard disk via Bootice. You then always boot from the USB stick and select the desired system. If the stick is not connected to the computer, the boot manager on the hard drive is used and the main system starts.

8. Install Windows on a virtual hard disk

Starting Windows from a VHD file: With Win NT Setup you create a virtual hard disk to which the tool copies the Windows files. The tool also adjusts the boot menu.


Start Windows from a VHD file: With Win NT Setup you create a virtual hard disk to which the tool copies the Windows files. The tool also adjusts the boot menu.

Use a virtual hard disk if there is no free partition or no second hard disk. The disadvantage: As with the USB installation, no function update is possible.

The quickest way to install is using the tool

Win NT Setup

Step 1:

Start Win NT Setup, click on “VHD >>>” and then on “Create”. Enter the name and storage location for the VHD file via “Search”. Enter the desired value after “Size of virtual hard disk”. For Windows 10 with 64-bit this should be at least 32 GB. Then click “OK” to create the VHD file. The VHD file is automatically integrated into the file system and the drive letter is entered under “Installation drive”.

Step 2:

Next, unzip the ISO file from the Windows installation medium

. In Win NT Setup click on “Browse” under “Windows installation files” and select the “Install.wim” file from the “Sources” folder of the unzipped ISO file.

Step 3:

The drive letter of the Uefi partition is already entered under “Start drive”. Then select the desired Windows 10 edition under “Options”, for example “01 – Windows 10 Home v20H1”.

Step 4:

Click on “Setup”, check the box in front of “Use the old boot menu version” and click on “OK”.

After Win NT Setup has transferred the files, restart Windows. Select the first entry in the boot menu, for example “Windows 10 Home (VHD)”. Then complete the setup. You can then change the order of the boot menu entries via Bootice (“BCD -› Easy Mode ”) and put the main system back in the first position in the list and set it as the default (“ Default ”button).

9. Set up Linux parallel to Windows

We describe the installation of

Linux Mint
. At

or other distributions, the procedure is the same, but the setup tools differ slightly.

Linux can be installed on its own hard drive. Now disconnect the system hard drive so that only the future Linux hard drive is connected. If that is not possible, Linux uses the existing Uefi partition and installs its own boot manager, which can be used to start Linux or Windows.

Step 1:

Boot the PC from the Linux Mint installation medium (Uefi boot entry). In the boot menu select “Start Linux Mint 20 Cinnnamon 64-bit”.

Step 2:

Start the setup by double-clicking the “Install Linux Mint” desktop icon. A wizard will guide you through the installation. You select “German” as the language and the German keyboard layout. Now put a tick in front of “Install multimedia codecs” for optimal support of audio and video formats.

Step 3:

In the “Installation type” window, leave the option “Erase hard disk and install Linux Mint” if only the hard disk reserved for Linux is connected. All files on it will be deleted. Otherwise select the option “Install Linux Mint next to Windows Boot Manager”. Click Install Now”. Check and confirm the partitioning of the hard disk and click on “Next”. Then set the time zone and set up a user account. You also use the password of this first user account for administrative tasks under Linux. When the installation is complete, click “Restart Now”. If Linux was installed on a hard drive together with Windows or the Windows hard drive was connected, a boot menu appears in which you can choose between Linux Mint and Windows.

Update boot menu: If the Windows hard disk was disconnected, reconnect it and start the Linux system in the next step. Open a terminal (Str-Alt-T), type the command

and press the Enter key. Confirm with your password and the Enter key. This will add the Windows boot manager to the boot menu. You can now boot from the Linux hard drive and choose between Linux and Windows. Or you can boot from the Windows hard drive if you only want to start Windows. Nothing has changed here.

10. Install Linux on a USB drive

The installation on a USB drive runs under Linux Mint as described in point 9. In the “Installation type” window, however, select “Something different”. After clicking on “Next” you will see a window with the hard drives or partitions found.

The USB stick is, for example, “/ dev / sdb”. It can be identified by the displayed size. Delete the partition on the stick using the “-” button. Then use the “+” button to create a new partition. After “Integration point” select “/” and click on “OK”. The USB stick must be selected under “Device for the bootloader installation”, in our example “/ dev / sdb”. Click on “Install now” and follow the further instructions of the wizard.

Virtualization as an alternative

For many users, the system installation in a virtual machine is sufficient. Here software can be tried out safely and you can experiment with system settings. In addition, the current state of the system can be saved in snapshots, which means that a previous state can be quickly restored. However, virtual machines are not, or only to a limited extent, suitable for applications that require a fast graphics card, such as video editing software or games.

Another disadvantage:

Windows requires its own license in a virtual machine and must be activated with a product key. Windows 10 can also be used for a while as a test without activation. There are just a few restrictions. In the “Settings”, for example, the options under “Personalization” are deactivated. Windows or Linux can be installed in virtual machines. Read detailed instructions for Windows 10

and for Linux



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