Solved Dell Laptop - Duplicate Windows Boot Manager Entry in BIOS

mccmw said:

my laptop has two Windows Boot Manager entries in the BIOS

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dacrone said:

View attachment 150315

what does msconfig show?

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mccmw said:

I tested and I can boot into Windows selecting either entry.

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Why Windows Still Boots Without a Windows Boot Manager Entry​

When you delete all Windows Boot Manager entries from the UEFI settings, Windows can still boot automatically from a GPT disk.
Here’s how that works under the hood

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1. The EFI System Partition (ESP)​

On a GPT disk, Windows creates an EFI System Partition (ESP), usually about 100–300 MB and formatted as FAT32.
Inside it, Windows stores its bootloader here:

Code:

\EFI\Microsoft\Boot\bootmgfw.efi

This file is the actual Windows Boot Manager.

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2. UEFI Boot Entries​

When Windows is installed, it creates a boot entry in the UEFI firmware’s NVRAM using a command like:

Code:

bcdboot C:\Windows

That entry appears in the BIOS/UEFI boot list as “Windows Boot Manager” and points to:

Code:

\EFI\Microsoft\Boot\bootmgfw.efi

If multiple Windows installations exist, you may see more than one of these entries.

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3. Why Windows Still Boots Without Any Entries​

When you remove all Windows Boot Manager entries, the firmware often still finds Windows automatically.
That’s thanks to the UEFI fallback boot mechanism:

1. If no valid NVRAM entries exist, the firmware looks for a default path on the EFI System Partition:
   
   Code:

   \EFI\Boot\bootx64.efi

2. Windows setup or repair tools often copy its boot manager to that fallback location:
   
   Code:

   \EFI\Microsoft\Boot\bootmgfw.efi → \EFI\Boot\bootx64.efi

3. UEFI detects that file and boots from it automatically — even with zero boot entries defined.

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Optional: How to See It​

You can confirm this by mounting the EFI System Partition and checking its contents.
Open Command Prompt as Administrator and run:

Code:

mountvol S: /s
dir S:\EFI\Microsoft\Boot
dir S:\EFI\Boot

You’ll usually see:

Code:

S:\EFI\Microsoft\Boot\bootmgfw.efi
S:\EFI\Boot\bootx64.efi

These files show that:

• bootmgfw.efi is the main Windows Boot Manager.
• bootx64.efi is the fallback loader that UEFI can boot even without defined entries.

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4. In Other Words​

• Deleting all Windows Boot Manager entries only removes firmware pointers.
• The EFI partition still contains valid bootloaders.
• UEFI automatically uses the fallback file (bootx64.efi) to start Windows.

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Summary​

What Happens	Why It Still Works
You delete all Windows Boot Manager entries in UEFI	UEFI firmware finds \EFI\Boot\bootx64.efi automatically
No manual boot entries exist	Windows installer already placed a fallback copy there
Windows still boots normally	The fallback mechanism takes over

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BCDBoot Command-Line Options

BCDBoot Command-Line Options

learn.microsoft.com

UEFI:

• BCDBoot copies the boot files to either the EFI system partition, or the partition specified by the /s option.
  
  BCDBoot creates the BCD store in the same partition.
  
  By default, BCDBoot creates a Windows Boot Manager entry in the NVRAM on the firmware to identify the boot files on the system partition. If the /s option is used, then this entry is not created. Instead, BCDBoot relies on the default firmware settings to identify the boot files on the system partition. By the UEFI 2.3.1 spec, the default firmware settings should open the file: \efi\boot\bootx64.efi in the EFI System Partition (ESP).

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