I just got a new Seagate and I installed it with my WD Windows drive. When I tried booting at first the system showed the error "Non-system disk" so I changed the boot order and that fixed the issue. However now the HDD doesn't show in Windows 10 either, nor in Device Manager or Disk Management. It only shows in BIOS. Also, when I make the secondary HDD the first in boot order, it shows some Intel Agent Media error or something saying "Media connection failure: check cable". But I have a laptop that shows the same and works alright, and it has only one hard drive installed in it. Help would be much appreciated.