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I have a computer that dual boots Windows 10 and 11. Windows 10 was installed first on a SATA SSD, while Windows 11 was installed afterwards to a separate M.2 SSD. Now that I've been on Windows 11 for a while, I want to wipe that the Windows 10 drive and use it elsewhere. However, if I unplug the Windows 10 drive my PC fails to boot past the BIOS. The Disk Management tool shows that my EFI System Partition is on the Windows 10 drive, meaning my Windows 11 install cannot boot without the Windows 10 drive.

How do I break this dependency so I can boot off my Windows 11 drive when my Windows 10 drive is disconnected?

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  • Shrink the Windows partition and recreate the EFI partition on the unallocated space that is created
    – Ramhound
    Aug 31, 2023 at 0:48
  • Something like this should help
    – Ramhound
    Aug 31, 2023 at 0:55
  • I didn’t intend to unilaterally close this question, the duplicate doe’s explain, what must be done. There is probably a better duplicate though
    – Ramhound
    Aug 31, 2023 at 1:11
  • The linked duplicate says how to resize an EFI partition, but not how to transfer one.
    – Stevoisiak
    Aug 31, 2023 at 2:16
  • The answer I read explains how to create a 500 MB EFI partition which is exactly what you need.
    – Ramhound
    Aug 31, 2023 at 2:35

1 Answer 1

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+50

The EFI partition is located by the BIOS by its partition signature, so can reside anywhere.

This seems like a simple method :

  • Use Disk Management, right-click C: and select "Shrink volume" to create an unallocated space at its end for the future EFI partition of at least 100 MB (I would suggest a bit more)
  • Install a partition editor and clone the EFI partition to this unallocated space. Use any product you like, for example the free AOMEI Partition Assistant Standard.
    See the article How to copy partition with Partition Assistant.
  • Open the computer, remove the Windows 10 disk and reboot
  • If this works, the removed disk can now be used elsewhere.
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  • The installer for AOMEI Partition Assistant lists system disk cloning as a paid feature.
    – Stevoisiak
    Sep 3, 2023 at 21:38
  • I purchased AOMEI Partition Assistant to clone my system partition. The cloned partition couldn't use the full unallocated space, so I had to make it a bit larger than 100mb. After cloning, I disconnected my Windows 10 drive and was able to boot off the Windows 11 drive. I then removed Windows 10 from my startup options.
    – Stevoisiak
    Sep 3, 2023 at 23:48
  • Strange - partition cloning is listed as available for the Partition Assistant free version. If that's incorrect, you should complain to AOMEI. Apart from that, do I understand correctly that the problem is now solved?
    – harrymc
    Sep 4, 2023 at 7:56
  • Yes, your solution worked. I'm waiting to see other answers before accepting since I had to purchase the software.
    – Stevoisiak
    Sep 4, 2023 at 18:31
  • If I had known that it would ask for payment for something that was advertised as free, I would have recommended another product. My apologies for that. But all is well that ends well and I'm glad to know that the problem is solved.
    – harrymc
    Sep 4, 2023 at 18:35

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