Moving EFI partition to another drive

I've ended up with this, the atatched image of Disk Management, don't ask why:

I want to move the EFI partition from disk4 to disk3.
Disk3 is the WIndows 10 installation I use but I want to remove Disk4 where the EFI partition resides.
How risky is it using something like AOMEI Partition Assistant to achieve this.
I definately don't want to loose the Win10 installation on Disk3

Would be grateful for any suggestions

Hello heywoodg and welcome to TF ,

If you don't already have backups of your drives, most of us here recommend using
Backup and Restore with Macrium Reflect

I would suggest making a bootable Macrium Reflect rescue USB too before your start moving the EFI partition.

I'm guessing you had Windows on Disk 4, then installed Windows on Disk 3 while Disk 4 was connected. The installation process saw the EFI partition on Disk 4, so it didn't create another on Disk 3. For this reason it is recommended to disconnect drives with other OSs when installing to a new drive.

steve108
It was a migration from Disk3 to Disk4 so obviously I couldn't disconnect any drive, I then decided to stick with Disk3 .

If you still want to stick with Disk 3 all you have to do is shrink C: drive partition by 100 mb. Create an EFI system partition and add the boot files to the new EFI system partition with the bcdboot command.

heywoodg said:

steve108
It was a migration from Disk3 to Disk4 so obviously I couldn't disconnect any drive, I then decided to stick with Disk3 .

If you ever want to migrate again, it is best to choose something that will do the job properly.

I use diskgenius for this task, it is excellent - free version does the job.

Does it matter where the EFI partition is located. It usually appears to the left of the Windows partition.
If I shrink the Win 10 partition on Disk 3 to accomodate the EFI partition, it will end up on the right of the Win 10 partition.
Is this okay?

NavyLCDR said:

If you still want to stick with Disk 3 all you have to do is shrink C: drive partition by 100 mb. Create an EFI system partition and add the boot files to the new EFI system partition with the bcdboot command.

Hi there
the easiest way --but you beat me to it !!!

Cheers
jimbo

If you want to keep Win 10 on drive 4 you must copy the EFI partition to drive 3 (not move)
- Open AOMEI Partition Assistant and make ~100M (unallocated space) at the beginning of drive 3.
- With AOMEI Partition Assistant copy the EFI partition from drive 4 to drive 3.
- Shutdown detach drive 4 (SATA or Power cable) and see if it boots from drive 3
- If it does, open MSconfig - boot tab and delete the other boot option (drive 4)
- Shutdown, detach drive 3 (SATA or Power cable) and attach drive 4.
- Boot from drive 4, open MSconfig - boot tab and delete the other boot option (drive 3)
On BIOS, set your boot priority.
To boot from a non priority drive, launch boot menu.