How do I enable dual boot?

Question

I've been using Windows since Ver 3.1 and I have mostly used Dual (or Multiple) Boot to select the latest or previous OS. Or even a second copy of the same OS, for security. I now have a new ASUS high-power tower PC and want to do the same. Windows 10 (Home) is on my C: drive, but of course I have to install Win 11. Since I have some legacy apps that run only on Win 10 I've done what I've always done before: use File Explorer to partition a D: drive and run a Windows 11 installer, expecting it to install Win 11 on the available D: drive and leave the old Win 10 on the C: drive. But it's not working. A new OS will only install on the C: partition, overwriting the previous Windows installation.

What am I missing? Is there a setting I've forgotten, to designate the D: partition as "installable"? How can I get it to install the new OS on the D: drive and leave the previous one on C:?

Aside: it's not the traditional rotating Hard Disk Drive I've always had before; I believe it's a solid state drive, so there may be something I need to do to prep the partition for an OS installation, but I don't know what.

Answer 1

To enable dual boot on your ASUS high-power tower PC with Windows 10 already installed, you need to follow these steps:

1. Prepare the D: Drive: Ensure that the D: drive is properly partitioned and formatted. You can do this using Disk Management in Windows. Right-click on the Start button, select "Disk Management," and make sure the D: drive is formatted as NTFS.
2. Install Windows 11: When you run the Windows 11 installer, make sure to select the D: drive as the installation destination. If the installer is not allowing you to select D:, it may be due to the drive not being formatted correctly or not being recognized as a valid installation target.
3. Using BCDBoot: If after installation you do not see both operating systems in the boot menu, you can use the BCDBoot command to add the new Windows installation to the boot menu. Open a command prompt as an administrator and run the following command:

      bcdboot D:\Windows
   

   Replace D:\Windows with the actual path to your Windows 11 installation.
4. Reboot: After running the command, reboot your PC. You should now see both Windows 10 and Windows 11 in the boot menu, allowing you to choose which one to start.

If you encounter issues with the installation process, ensure that your BIOS/UEFI settings are configured correctly for dual booting, and check that the D: drive is set up as a primary partition suitable for OS installation.

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References:

• Repair the boot menu on a dual-boot PC
• BCDBoot Command-Line Options

Answer 2

Hi,

Likely C: disk in Win11 has D: letter in Windows 10.

Please show Disk management window from both systems.

Answer 3

(Apologies for the delay; I've had medical issues to deal with.)

I don't entirely understand your point, but you got me to take a closer look at the drive settings. I now see that the disk properties of C: (Windows 10 Pro) and D: (where I want to install Windows 11) are different. D: appears to be a simple data drive, much like F:. What can I do to make D: a system drive so I can install Windows 11 onto it as a dual boot?

(Apologies for the large font and spacing. I don't have any of my apps working.)

Partition Disk #0, Partition #0

Label: Healthy (EFI System Partition)

Partition Size 260.00 MB (272,629,760 bytes)

Partition Starting Offset 1,048,576 bytes

Partition Disk #0, Partition #1

Label: OS (C:) Healthy (Boot; Page File; Crash Dump; Basic Data Partition) NTFS

Partition Size 189.98 GB (203,992,407,552 bytes)

Partition Starting Offset 290,455,552 bytes

Partition Disk #0, Partition #2

no Label: Healthy (Recovery Partition)

Partition Size 1.31 GB (1,407,188,992 bytes)

Partition Starting Offset 204,283,576,320 bytes

Partition Disk #0, Partition #3

>> Label: D: Healthy (Basic Data Partition) NTFS <<

Partition Size 198.36 GB (212,989,902,848 bytes)

Partition Starting Offset 205,690,765,312 bytes

Partition Disk #0, Partition #4

Label: E: Healthy (Windows Boot USB Drive Images) NTFS

Partition Size 186.90 GB (200,686,960,640 bytes) 100% free

Partition Starting Offset 418,680,668,160 bytes

Partition Disk #0, Partition #5

Label: F: David Healthy (Basic Data Partition) NTFS

Partition Size 351.56 GB (377,487,360,000 bytes) 92% free

Partition Starting Offset 619,367,628,800 bytes

Partition Disk #0, Partition #6

Label: F: David Healthy (Basic Data Partition) NTFS

Partition Size 24.00 GB (25,769,803,776 bytes)

Partition Starting Offset 998,166,757,376 bytes

Partition Disk #0, Partition #7

no Label: 1.22 GB (Unallocated)

Partition Size 260.00 MB (272,629,760 bytes)

Partition Starting Offset 1,023,936,561,152 bytes

Partition Disk #0, Partition #8

Label: RESTORE (Basic Data Partition) NTFS

Partition Size 24.00 GB (272,629,760 bytes)

Partition Starting Offset 998,166,757,376 bytes

Partition Disk #0, Partition #9

no Label: (Recovery Partition)

Partition Size 260 MB (272,629,760 bytes)

Partition Starting Offset 1,023,936,561,152 bytes

Answer 4

Keep the same boot drive to have a simple choice of system during boot. Just install another Windows copy to another partition.