You're trying to use these old drives as boot drives in a new machine?
No, I'm saying they only work if they're actually connected to the motherboard as such. in a hard drive enclosure, they're not recognized properly.
My best case scenario goal is to make a drive image out of them all. Next best thing is just a simple way to connect them to the computers without having to constantly shut down, plug them in, and start the computer again to have the drive "work".
I'm not great at diagnosing HDD issues - but I think your issue pertains to the formatting of the drive (FAT32 vs. NTFS)
No, not at all. The problem is centered around my use of an external thing. I guess the controller inside somehow doesn't recognize it, or it's formatted in a way that for some reason only the bios will recognize? I don't know. The issue is that it will ONLY work when plugged into the motherboard, but this is an extremely unwieldy way of copying dozens of old hard drives. I'm just wondering if anyone knows why they wouldn't work, how to find a solution that does work, or anything.