Added new HDD but disappears when connect external HDD

[jimmys71]

Added SATA HDD to system with a SSD. Setup and working well but when i connect an external HDD the new HDD disappears. If I disconnect the external HDD and reboot the new HDD reappears. Have I set it up incorrectly?

 

[lukelaw]

I think they both have the same partition letter, just google how to fix it

 

[jimmys71]

I just tried it again and know all 3 are showing. And, no, it wasn't the same drive letter.