How to install two isolated windows 8.1?

Question

Windows

I have two ssd drives in the block.
I would like to have "their" Windows on both, which would NOT see any files or logical drives of another ssd.
It would seem that in the BIOS to disable either one or the second, but I do not have the ability to disable (make inaccessible) ssd in the BIOS to choose from.
In other words, after booting, no matter what Windows I am in, I see the contents of the second ssd.

Answer 1

Encrypt both disks, each under its own Windows :-) Cheap and cheerful.

Answer 2

Well, by the way, the option with encryption is not so bad... Otherwise, unless you turn off the letter from the disk of another Windows in the settings of each Windows...
The system will see the disk, but it will not be able to read and write to it.

Answer 3

On an additional computer I use Windows XP, Windows 7 and Windows 10 on separate SSDs. Operating systems do not physically see each other's disks.

because

Answer 4

In other words, after booting, no matter what Windows I am in, I see the contents of the second ssd.

What prevents you from turning off the disk in windows itself?