Question Making main drive bootable ?

[Arkatakor]

I used to have a 512 GB SSD as my primary Windows boot drive. I bought a new 1TB NVMe SSD and installed Windows on that. In so doing I left the old 512 GB SSD as is, with Windows still installed on it and whatnot.

I am in a situation now where if I remove the old 512 drive my system refuses to boot into windows. So in short, my system boots into my 1TB drive via the 512 drive. I suspect this has something to do with fact that the old 512 drive has an EFI partition on it and the 1 TB one does not. My current drive setup can be viewed here . The drive I want to boot into is C: (top drive in pic).

I am running an ASUS X99-DELUXE using a UEFI BIOS.

Is there a way I can make my C: drive in the pic bootable? Can that be done via windows? I suspect I need to add an EFI system partition to it; if so steps how to achieve that would be appreciated.

EDIT: my goal is to remove the 512 drive completely, however doing so makes my system non bootable. I am trying to use the 1TB drive as my system / boot drive and have my D drive as my storage drive. Therefore I need (apparently) to create a UEFI partition on the 1TB drive (see pic) and would like to know if its possible to do so without doing a clean OS install.

 

[Lutfij]

You're advised to remove(disconnect) all drives from your platform that you don't intend to install the OS on. I would backup all mission critical off of both drives, then format and wipe both drives. Remove the larger drive, then install the OS on the smaller drive. Once OS install is complete, you can manually install all drivers onto your laptop and then add the larger SSD, as your storage drive.

 

[Arkatakor]

You're advised to remove(disconnect) all drives from your platform that you don't intend to install the OS on. I would backup all mission critical off of both drives, then format and wipe both drives. Remove the larger drive, then install the OS on the smaller drive. Once OS install is complete, you can manually install all drivers onto your laptop and then add the larger SSD, as your storage drive.

My goal is to remove the 512 drive completely. I already have my D drive (2 TB) for storage. Updated the OP to specify this.

I am posting here because I would like a solution that does not involve doing another full Windows install. I simply want to see if its possible to add a UEFI partition to my existing main drive which has Windows 10 on it, so my system can boot off that.

 

[SkyNetRising]

EDIT: my goal is to remove the 512 drive completely, however doing so makes my system non bootable. I am trying to use the 1TB drive as my system / boot drive and have my D drive as my storage drive. Therefore I need (apparently) to create a UEFI partition on the 1TB drive (see pic) and would like to know if its possible to do so without doing a clean OS install.

That can be done. Yes.

Execute from elevated command prompt.
If you get any errors, then stop immediately!
(and show screenshot with command output).

diskpart​

list disk​

select disk 0​

(select 1TB OS disk)​

list partition​

select partition x​

(select 931GB C: partition, x=1 or x=2, replace x with appropriate number)​

shrink desired=500​

create partition efi​

format fs=fat32 quick​

assign letter=H​

exit​

bcdboot C:\windows /s H: /f UEFI​

Last message should be "Boot files created successfully".

What is an Elevated Command Prompt?

Computer dictionary definition for what Windows elevated command prompt means including related links, information, and terms.

www.computerhope.com

 

[SkyNetRising]

I would backup all mission critical off of both drives, then format and wipe both drives. Remove the larger drive, then install the OS on the smaller drive.

That is such an excessive course of action.
You did a small mistake, then do full wipe and reinstall. Although fix is easy and simple.