If you have purchased a new PC with Windows 10 or if you have upgraded to Windows 10, but you also want to have an installation of Windows 7 on your computer, you must install Windows 7 (or even Windows 8.1), keeping Windows 10, in dual boot mode . This is a relatively easy system operation, which however requires some requirements and a little preparation.
First of all you need to have a backup of your important files before proceeding with the installation of Windows 7 on your PC with Windows 10.
Although, for now, there should be no compatibility problems, it is important to check on the computer manufacturer's website (if it is a new laptop already pre-installed) that there are drivers for Windows 7.
Another important point is that related to the legal license.
If you have updated Windows 7 or 8.1 to Windows 10, you cannot use the product code of that Windows 7, but you will need to find a new one that is not already in use on another PC (see also: On how many computers can I install Windows " > Where to download each version of Windows
The procedure to install Windows 7 or 8.1 in dual boot on a PC that already has Windows 10 begins with the creation of a partition on the disk, dividing the current one in two so that one remains Win10 while on the other one can install Win7 or Win8.
On the computer, depending on its configuration, there may already be other partitions, such as the recovery partition prepared by those who sold us the PC or the partition reserved for the system that remains hidden and must never be touched.
To see the situation of the disk and the partitions, in any version of Windows, just go to Control Panel> System> Administrative Tools> Computer Management .
Go to disk management to see the active partitions on disk 0, where there should be partition C: where Windows 10 is installed.
Before dividing the partition to create a new one, it is important that a backup of the working installation of Windows 10 is made so that, in case something goes wrong, you will not lose important data and you can restore everything easily.
To do this, use Easus Todo Backup or other programs to clone the disk as a system backup image.
Next, split partition C in two from the Windows 10 Disk Management utility.
Then open Disk Management (as seen above), right click on the partition of Windows 10 and press on Shrink Volume .
Depending on how big the volume is, divide it in two or reduce it by a measure necessary to use Windows 7 on the same computer, therefore at least 70 or 100 GB.
100 GB equals 102400 MB so you can write this value as space to be reduced.
Click the Shrink button and wait until it is complete.
Now, next to partition C: you should see an unallocated space of the predetermined size.
Right-click on the unallocated space and format it (if it is an SSD use quick format) to create a new simple volume with a recognizable name.
Installation of Windows 7 or Windows 8.1
The only difficulty in installing Windows 7 or 8.1 in dual boot on a PC where Windows 10 is already present is that of managing the start menu of the computer.
It is therefore necessary to enter the BIOS or UEFI to change the boot order so that the PC, just switched on, does not load Windows 10 from the internal disk, but loads the contents of the DVD or USB stick with the Windows installation files 7.
If you don't have only the DVD or ISO of Windows 7 or Windows 8.1, see here how to create the Windows 7 installation USB stick.
If there are difficulties, I refer to the guide on how to change the boot order of the computer to load the installation USB stick instead of Windows 10.
the installation process of Windows 7 or Windows 8.1 can now start automatically and continue to the end following the guided procedure.
The only important point is where you have to choose which partition to install the system in, choosing the empty one just created.
After reading and accepting the license terms, you should be asked to choose the type of installation where you have to select the Custom or advanced or customized one.
You can then choose where to install Windows by highlighting the previously created partition and continue.
After Windows 7 (or Windows 8) has finished the installation process, you will need to install the computer drivers and all updates for Windows 7.
Windows 7 and Windows 10 will be two separate and independent installations and you can turn on the computer by choosing to use one or the other.
It is not possible to use both systems together.
The choice of which system to boot can also take place before starting using a program such as EasyBCD, an ideal program to manage the dual boot of two systems on the same PC.
Without external programs, on the other hand, you can customize the time in which to display the menu for choosing the system to start from MSConfig, press the Windows-R keys together, type msconfig and press Enter).
At boot options, you can choose the default operating system and the timeout of choice.
In the case of errors in startup, refer to the article on how to restore boot loader, MBR and startup of the Windows computer .
