Question Automatic repair loop

Aug 20, 2019
Hi. I had two separate harddisks with windows installed on two different computers. Recently i formatted one of the hardddisks and decided to use that harddisk in my computer. When i attached the harddisk to the motherboard via SATA and started the computer i got into the Automatic repair loop. I looked through troubleshooting here in the forum and i kept pressing F8 repeatedly when the computer was starting and i was prompted into the Motherboard BIOS settings and there was the harddisk which i had erased the windows from had been chosen as my default boot harddrive. When i changed it to the harddrive to the one that has the windows then it became all normal and the automatic repair loop was gone and i got into windows. I was just wondering if i did the right thing. Sorry if this is a noob question but i am fairly new to computer parts building from scratch. My question however is why did my motherboard chose the harddrive that i just wiped all data from as my default boot drive? Any insights and help would be greatly appreciated. Thanks in advance!