Bios not recognising other Hard Drives

Received new PC today (it’s awesome, thank you). I’ve put my other hard drives in and they’re recognised in Windows, but when I got into Bios, as I want to boot from my other hard drive, Bios isn’t recognising then only the new hard drive.

Just wondering if anyone can help?

Many thanks

THis may be because your new PC will likely be using UEFI secureboot and your old drives use MBR partitions.