EDIT: SOLVED AFTER TWAEKING TWEAKING BIOS.!
Greetings,
I upgraded my PC with Gigabyte B450 Elite and Ryzen 5 3600, and few other parts. Kept only the old hard drive, WD Purple 1 TB.
The hard drive has 4 partitions, I had taken a backup of C drive as I knew Windows will be installed there but...