I GOT a NEW MSI gaming pc. I slotted in my two old hdds and ssd from my old computer. I went into the bios and tried to get the computer to boot from my old windows installation instead of using the windows that the computer came with, but the bios isn't detecting it. I have enabled the SATA ports in the bios. When I go into windows explorer with the new installation, my drives are shown and I can ACCESS them.

My bios is a H130M pro-m2 plus (ms-7c08).

In short, wanna boot new prebuilt from old hard drive, but bios can't see it.You cannot simply move Windows drives from 1 PC to another and expect it to boot...

All your data should still be there though.Well, the weird thing is, I was able to get my partners old windows to boot from his new computer which is the same prebuilt.That is total Luck...

I get the feeling it's not. Shouldn't my drives be shown in the bios?Yes...if BIOS doesn't see them they arent CONNECTED proper or dead...try 1 at a timeOk, in the system info in the bios, it is reading my drives. It's just not seeing my old windows

I guess if I can't get it to run off my old drive, how would I go about transferring all of my settings to the new installation. I don't think there's enough room in the new partition for what I had in my old one.Was the old SSD with the windows you want to boot on was it Windows 10 as an upgrade from an earlier version of windows ?
Check in the bios that the drives are ACHI and perhaps try with secure boot off. On the post LED's is the boot LED stuck red?
Also was the computer supplied with an M2 Drive fitted?

As you are trying to boot from an SSD can you confirm again it still boots in your old machine.

Yes, it was an upgrade to windows 7. And I'm ACTUALLY trying to boot from an hdd.I got it working 👍. Went into the windows configuration and boot options and disabled a bunch of stuff.