Whenever you have duel Windows Operating Systems across different physical hard disks, the system partition mostly would be on the first disk. For example, you have Windows 8.1 on your first hard disk. Then you add another SSD to install Windows 10 as the secondary OS. Now you need to remove the first hard disk or format it completely. But the things is, you can’t unplug or format the entire old hard disk, because your computer may have the boot sector (System partition) on the old hard disk. If you remove it without doing proper changes in the system, the Windows 10 will not boot.
In this guide let me show the simple methods to change/move the System partition to different hard disk in Windows 10 or 8.1. We will not use any free or paid disk management tools for this. Let’s use the Windows utility, provided you have the bootable medium of the OS (in this case, Windows 10) with you.
Recently I switched to Windows 10 from Windows 8.1 Operating System. I was having my first hard disk with Windows 8.1. I added new SSD hard drive for Windows 10 and it worked great. Later, I wanted to get rid of Windows 8.1 and its storage to utilize for other purposes. But there was a catch when I tried to format the entire first hard drive. Even though I booted my computer from Windows 10 (from newly added hard disk), I could not format a particular partition which was created earlier while installing Windows 8.1. Because that was the ‘System’ partition on my computer.
What is System Partition?
The system partition is the one having the information that will be read by the booting process at the first place, basically, it tells the hardware to where to look for Windows booting files such as bootmgr. You can find more information about types of partition on Microsoft site here.
In my case even though I have connected the new hard disk on SATA 0 port, that’s why the disk has become Disk 0, but the Disk 1 was having the system partition earlier. I missed to take the screenshot before the changes, but I’m sure below screenshot will give an idea how it was.
I found several suggestions on the internet to change the system partition to a different disk, but they did not work. Sometimes, you need to use disk utility programs to move the partition. We can avoid them by using the Windows bootable medium either DVD or USB. Here is the easy way I found to change the system partition to different disk on Windows 10/8.1.
Change The System Partition to Different Disk in Windows 10
1) Restart the Windows 10 computer and log in to BIOS.
2) Change the hard disk boot priority. Make the hard disk where you want to have system partition as first boot hard disk.
In my example, the SSD Disk 1 (SATA Port 1) was set as the first boot disk, so I had to change Disk 0 (SATA port 0) as the first boot hard disk.
In another case, you can disconnect the other all hard disks from the computer and connect the only hard disk where you need to move the system partition. In my example, it is the SSD which has Windows 10 on it.
Save the changes on the BIOS and reboot the machine.
3) Mostly the Windows 10 will not boot. Because there is no system partition (or information) on the first boot hard drive now. You need to have Windows 10 bootable DVD/USB to boot the machine.
4) Boot the machine with Windows 10 DVD/USB and select ‘Advanced options’ under Troubleshoot.
Here you need to select ‘Automatic Repair’.
Windows 10 will automatically detect and repair the startup issues, I assume during this process it makes the first partition of first hard disk as ‘System partition’.
5) Once repair completed and rebooted successfully, you can use Windows 10 without any issues. Now if you go to disk manager, you could see that System partition had been moved to different disk where you wanted.
You can connect back the other physical hard disks once this completed successfully.
Now you should be able to format or delete partition which was system partition earlier. In this way, I successfully managed to move the system partition in Windows 10 to different hard disk/partition without using any third-party tools/software.
I hope this guide is helpful for the users who migrate to Windows 10 from different hard disks on the same computer.