[SOLVED] How to change windows boot manager drive?

Dec 8, 2021
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I have an SSD [C:] that came with a new laptop, and a separate SSD [E:] that contains all my files. I want to make the E: drive the primary boot drive. Both have Windows 10 installed on it.

I cannot do this through the BIOS so I'm assuming it has to do with where the Windows Boot Manager is?

Maybe this is irrelevant, but the older SSD is MBR while the one that came with the laptop is GPT.
 
Solution
  1. I basically had to format the 500GB from MBR to GPT. [AOMEI]
  2. Create an EFI partition (size=100mb) on the 500GB. [diskpart]
  3. Install Windows 10 on the 500GB, but still kept the files of course. [USB]
  4. Wipe the 250GB. [diskpart]
  5. Create a primary partition on the 250GB and assign a letter. [diskpart]

USAFRet

Titan
Moderator
OK...

You can't use the old OS that lives on the 500GB as you OS drive.
Windows is not modular like that, especially between laptops.

Can you access your personal files on the 500GB drive?
Not the applications, just whatever files you have on there.
 

USAFRet

Titan
Moderator
Yes I can access everything there.
OK then....
Copy whatever files you want from that to some other storage location. An external drive, DropBox, whatever. (NOT the 250GB drive in the system)

Then...
Power OFF
Physically remove the 250GB drive.
Full wipe and reinstall on the 500GB drive.

OS, drivers, and everything else.
 
Maybe this is irrelevant, but the older SSD is MBR while the one that came with the laptop is GPT.
If your laptop bios has the option you can just try to switch from secure boot to legacy and see if it boots from the old drive.

You can also get the free version of easybcd, go to BCD deployment and write a new mbr to the 500Gb disk and install an bcd store to it so that the system can boot from it.
Or you can edit the bcd of the 250Gb disk to include the 500Gb disk.

Windows 10 is pretty good in booting with wrong drivers but it's no guarantee that there wont be any problems.
 
OK then....
Copy whatever files you want from that to some other storage location. An external drive, DropBox, whatever. (NOT the 250GB drive in the system)

Then...
Power OFF
Physically remove the 250GB drive.
Full wipe and reinstall on the 500GB drive.

OS, drivers, and everything else.
That is rather "nuclear" option.

You could just
copy all user data from E: to C:​
clean 500GB disk​
clone 250GB disk to 500GB disk​
remove 250GB disk and boot from 500GB disk,​
reconnect 250GB disk and clean/repartition/reformat it.​
 

USAFRet

Titan
Moderator
If your laptop bios has the option you can just try to switch from secure boot to legacy and see if it boots from the old drive.

You can also get the free version of easybcd, go to BCD deployment and write a new mbr to the 500Gb disk and install an bcd store to it so that the system can boot from it.
Or you can edit the bcd of the 250Gb disk to include the 500Gb disk.

Windows 10 is pretty good in booting with wrong drivers but it's no guarantee that there wont be any problems.
I would not go down that road.

Either a fresh install on the 500GB, or clone from the 250GB to the 500GB.
 
Dec 8, 2021
9
0
20
  1. I basically had to format the 500GB from MBR to GPT. [AOMEI]
  2. Create an EFI partition (size=100mb) on the 500GB. [diskpart]
  3. Install Windows 10 on the 500GB, but still kept the files of course. [USB]
  4. Wipe the 250GB. [diskpart]
  5. Create a primary partition on the 250GB and assign a letter. [diskpart]
 
Last edited:
Solution