Unable to Select Boot Drive in BIOS After Installing Windows 11 on Multiple SSDs

Question

Basically I have a version of Windows 11 that I have been using on a Sata SSD, yesterday I got a new m.2 SSD that I mounted on the motherboard but did not detach the Sata SSD. I did a fresh installation of windows 11 on the Sata SSD since I had not formatted the pc for quite a while and because the m.2 SSD is about 6 times faster than my old Sata SSD. Now though, after installing windows 11 on the m.2 SSD, I am on the latter after choosing during the first boot after installing from USB, whether to run windows from the m.2 or the Sata. Since then, however, I can't get back into the Sata SSD since from BIOS only the Sata SSD is indicated but not the m.2 (of which the Sata SSD is already selected), although windows starts from the m.2. What's more, I also have selections for boot partitions for Ubuntu (which starts GRUB 2.06) and Kali (which starts the corresponding GRUB) that I installed some time ago but have now uninstalled. I would like to point out that both disks work properly and are correctly detected by the m.2 Windows 11 file explorer.

So in short, how do I make it so that I can boot one windows instead of another by selecting it from bios? And how could I do to remove those 2 versions of GRUB from the Sata SSD?

I have already tested, using the Windows 11 installation USB, restoring via CMD using the bootrec /fixmbr command, or from Windows from m.2 with the bcdboot D:\Windows command. Getting poor results, however.

Answer 1

Eventually I managed to find out that in the m.2 SSD the windows installer did not create the EFI system partition and using ChatGPT I was able to get the following steps to create this EFI partition without having to reinstall Windows 11 from scratch.

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If you don't want to reinstall Windows 11 from scratch, you can create an EFI system partition (ESP) without reinstalling the operating system by following these steps:

Note: Modifying disk partitions can potentially lead to data loss, so it's important to backup your important data before proceeding.

1. Open the Disk Management utility:

• Press Windows Key + X and select "Disk Management" from the menu that appears.

• Alternatively, you can search for "Disk Management" in the Windows 11 search bar and open the utility.

2. Shrink an existing partition:

• In the Disk Management window, right-click on an existing partition (e.g., the system partition or another data partition) and select "Shrink Volume."

• Specify the amount of space you want to shrink. Make sure to allocate enough space for the EFI system partition (usually around 200 MB).

• Click "Shrink" to create unallocated space on your hard drive.

3. Create the EFI system partition:

• Right-click on the unallocated space you created and select "New Simple Volume."

• Click "Next" on the New Simple Volume Wizard.

• Specify the size for the EFI system partition (e.g., 200 MB) and click "Next."

• Assign a drive letter to the partition or leave it unassigned. Select "Do not format this volume" and click "Next."

• Click "Finish" to create the EFI system partition.

4. Format the EFI system partition:

• Open File Explorer and locate the newly created EFI system partition. It should have a drive letter or be listed as an unassigned partition.

• Right-click on the partition and select "Format."

• Choose the file system as FAT32 and provide a name for the partition (e.g., EFI).

• Enable the "Quick Format" option and click "Start" to format the partition.

5. Set the partition as an EFI system partition:

• Press Windows Key + X and select "Command Prompt (Admin)" or "Windows PowerShell (Admin)."

• In the command prompt, type diskpart and press Enter to launch the DiskPart utility.

• Type list disk and press Enter to view the available disks.

• Type select disk <disk number> (replace <disk number> with the disk number of your system disk) and press Enter.

• Type list partition and press Enter to see the partitions on the selected disk.

• Identify the newly created EFI partition (it should be listed as an empty partition).

• Type select partition <partition number> (replace <partition number> with the partition number of the EFI partition) and press Enter.

• Type assign letter=s and press Enter to assign the drive letter "s" to the EFI partition.

• Type exit and press Enter to exit DiskPart.

6. Reconfigure the boot settings:

• Open the Command Prompt or PowerShell as an administrator again.

• Type bcdboot C:\Windows /s S: and press Enter. (Replace "C:" with the drive letter of your Windows partition if it's different.)

  • This command will copy the necessary boot files to the EFI partition and set it as the boot partition.