I want to connect my old hard drive to my PC. But windows 7 was installed on old hard drive. I am using win10 on new PC. If I connect old HDD to new PC. How the PC would turn on Win7 or Win10. I want to format win7 on old HDD. Please help me!!!
After you connect win7 drive, boot into BIOS and check boot priority and correct it, if necessary. Connecting additional drive may change boot priority.
If win10 drive is first in boot order, pc will boot into win10.
If win7 drive is first in boot order, pc will try to boot win7 and possibly fail (may also succeed in some situations).