If you wanted to boot via the BIOS you should unplug the other HD/SSD when installing each OS. Then set the HD which you want to boot first as first HD in priority in BIOS setup.
But since you already have a Windows Boot Menu, the HD marked System in Disk Mgmt should be set first in priority to boot.
On some BIOS this boot order might be ignored with the non-System HD trying to boot first. As Theog says you need to change the ports to correct it in this case.