Question HDD Accessible in Windows but not in UEFI Firmware

[Quail0rd]

Hello, my mom recently got a new computer. It was pre-loaded with an SSD with Windows 11. I installed the HDD from her previous PC and was able to move files to the new drive so she had her bookmarks and pictures. However, after a few days, she determined she didn't like Windows 11 so I thought, no problem, I'll just boot windows 10 from the old HDD.

Well apparently the UEFI doesn't detect the old HDD. I don't understand this. When I check in Windows, I can see the old HDD in addition to the SSD Windows is running on, the old HDD clearly has all its files. I tried uninstalling the old HDD.

https://imgur.com/qxjpOh7

View: https://i.imgur.com/qxjpOh7.jpeg

I suspect the only solution is to unplug the SSD in the new computer...the problem with that is I don't physically see the new SSD. I was convinced at first that it didn't even come with one. I think it must be behind the motherboard, at any rate, it'll be a hassle to get to in this stupid little compact case. I wish she had just let me upgrade her old PC, honestly.

https://imgur.com/p7GR6oN

View: https://i.imgur.com/p7GR6oN.jpeg

Pictures show the HDD is accessible in Windows 11 but not in the UEFI Firmware. How can I boot from the HDD if it doesn't show in the UEFI?

Thanks,
Shannon

 

[USAFRet]

so I thought, no problem, I'll just boot windows 10 from the old HDD.

Yeah, that rarely works, in the best of circumstances.

If the old drive was a Legacy install, it will NOT work.

Even if you can make it appear in the boot order, it likely will not work correctly.
And then, the licensing will also fail.

 

[SkyNetRising]

Well apparently the UEFI doesn't detect the old HDD. I don't understand this.

Legacy support is disabled (5th row in your 1st screenshot).

Windows on HDD is probably installed in legacy mode.
To boot from HDD, you have to enable legacy support.

But even then it's not guarantied to work.

 

[Quail0rd]

Legacy support is disabled (5th row in your 1st screenshot).

Windows on HDD is probably installed in legacy mode.
To boot from HDD, you have to enable legacy support.

But even then it's not guarantied to work.

This worked- it shows up, however, how do I set it to boot using the HDD each time the pc? I set the HDD above the SSD in the Legacy boot order. I can only boot by going to Settings > System > Recovery Advanced Start Up, restarting, selecting "use a device" and selecting the HDD.