Recently i bought an SSD and replaced an old HDD which needed replacement. Today I decided to remove the old HDD, but when I fired my pc up it gave me the message: "reboot and select proper boot device". I already installed windows on the new SSD and when I reconnect the HDD it doesn't give the message and works normally.
Specs:
SSD: Samsung 860 QVO 1TB
HDD: WD Blue 500GB (2010)
CPU: Intel Core i3-8350K
GPU: Nvidia GTX 1050-Ti
RAM: HyperX Fury DDR4 2666 C15 2x4GB
MBD: MSI Z370 GAMING PRO CARBON (MS-7B45)
Edit: I tried formatting the old drive, but still nothing.