2 hard drives, 2 operating systems...

Dr.Sadin · February 16, 2017

Hello all!

Ive got a problem...lemme tell you a story

First, i bought a pc with hitachis 500GB drive, and upgraded from win7 to win10.

After that ive bought a New pc, which came with hitachis 1TB hard drive...for some time my primary drive was 500GB, but i decided to sell old pc so i made a Windows 10 installation CD and installed it on new (1TB) drive...

2 days ago (after rearranging cables in case) my pc started to give me message " reboot or select proper Boot Device..etc"

It took me some time to understand that i changed those 2 hard drives on mobo, and BIOS wanted to Boot from 1TB drive which is fine, but not working.

Only way to Boot into its system is to select old hard drive as primary, and then its gonna load and ask me which operating system do i want..

Then i have both systems available to choose (old and new one)

Where did i make a mistake?

Mira Yurizaki · February 16, 2017

I'm going to assume you did the following:

Installed the 500GB drive into the new computer with the 1TB drive
Reinstalled Windows on the 1TB drive while the 500GB drive was in there and was selected as the primary boot disk

If this is true, what most likely happened is the 500GB drive has the bootloader on it to handle both Windows installs on the two drives. If you want to boot from the 1TB drive, you're going to have to create a bootloader for it. You can get an idea of how to do it from:

Alternatively you can reinstall Windows 10 on the 1TB drive, but this time making sure it's the only drive plugged into the system