By Emily / Last Updated April 25, 2022

Why change primary hard drive in Windows 10?

“I have a laptop with SSD 32 GB - C drive and I later added additional SSD with 240 GB D drive. Windows was installed on C drive. Currently, all new programs are getting installed by default on C drive. I do not have the option to choose where they will be installed. So, I want to chang the local disk from C to D and installed Windows 10 on D drive. How can I change the primary drive and make the second bigger SSD drive as the primary one? Anyone can help? Thank you, ”

From the above user case, we can know that users might want to replace a smaller older hard drive with a bigger new hard drive when the current hard drive is almost full of system files, programs and other personal files. Besides that, another main reason for changing startup drive is to upgrade a slow hard disk to a faster SSD drive when your Windows OS is now installed on a  mechanical traditional hard disk drive that tends to slow in accessing data.

How to change startup hard drive in Windows 11/10/8/7?

To set primary hard drive in Windows 10, or make the second hard drive as the primary drive, you can fresh or clean install Windows OS on the new SSD/HDD, or install Windows on a second drive. Or you can change the primary hard drive by migrating OS to another disk. Those are two practical methods and you can follow the tutorials to get the complete info.

Method 1. Change boot disk by fresh or clean installation (complex)

To clean install the Windows on another disk and make it bootable, you need to prepare an empty USB (8GB min), download Windows Media Creation Tool and Windows product key (activate after installation).

Before proceeding: check whether the partition stlyes of the target and source primary drive are same. If not, you had better first convert the destination disk to MBR or GPT in case that you meet the errors: “Windows cannot be installed to this disk. The selected disk is of the GPT partition style” or “The selected disk has an MBR partition table”.

Step 1. Download Windows Media Creation Tool, launch it and choose “Create installation media (USB flash drive, DVD, or ISO file) for another PC” and click “Next”.

Create Installation Media

Step 2. Select the empty USB as the target drive, and follow the onscreen instructions to create a bootable USB drive for installation.

Choose USB Drive

Step 3. Then remove the old system disk, insert the new disk you want to make as new primary drive and the bootable USB to your computer, reboot it, enter BIOS, change boot priority and boot computer from the installation media.

Step 4. Once the PC boots from the USB drive, Windows 10 will automatically enter setup mode. Setup preferences, and then click on “Next” > “Install now”.

Windows 10 Setup

Step 5. Input the license key, or skip it and activate it after Windows install completes.

Step 6. In the “Where do you want to install Windows” screen, click on “Custom: install Windows only (advanced).” and choose your new drive. Click “Next” to install OS on the target disk.

Step 7. After the installation, restart your PC, enter BIOS to change the boot drive by setting SSD as the OS drive.

Change Boot Order

At last, you can shut down your computer, remove the installation USB drive, reinsert the old hard drive to your computer and use it as a data drive.

Method 2. Change startup hard drive by OS migration (straightforward)

If you want to change primary hard drive in Windows 11/10/8/7 without reinstalling system, you can make use of a professional partition manager that supports to migrate system another HDD or SSD. Then the “Migrate OS to SSD Wizard” of AOMEI Partition Assistant Professional can meet your requirements best. It enables you to transfer system between HDD and SSD no matter whether they are of the same partition style or not. And you don't need to worry that you cannot boot Windows from the new disk afterward. 

Download Free Demo Win 11/10/8.1/8/7/XP
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▸Back up system in case that some improper operations or accidents lead to data loss.
▸If you are changing primary hard drive from MBR to GPT, you have to ensure your motherboard supports UEFI or EFI boot mode because it is necessary to upgrade Legacy to UEFI for a smooth boot.
▸Connect the destination disk you want to make the new boot hard drive to your PC and ensure it is detected.

Step 1.Install and launch AOMEI Partition Assistant Professional. Click “Migrate OS to SSD”.

Migrate OS to SSD

Step 2. Choose an unallocated space on your destination disk and click on “Next”. If there is not unallocated space, you can tick “I want to delete all partitions on this disk to migrate system to the disk”. If you have to choose this option, please back up all necessary data on the disk beforehand.

Select Space

Step 3. You can specify the size or the location of the new system partition on the new disk.

Resize Partition

Step 4. Then comes a boot note. Read it carefully if necessary and click on “Finish”.


Step 5. Click on “Apply” to commit the pending OS migration operation.


Wait for the process to complete, and then you can restart your computer, enter BIOS setup, change boot order to boot computer from the new startup disk.

You may also want to know...

If you desire to move everything on the current boot disk to another disk and make it new system hard drive, please try “Disk Clone Wizard” feature, which will clone one hard drive to another hard drive and make it bootable.

Disk Copy Wizard

The above content focuses on how to make a second hard drive primary in Windows 11/10/8/7. Some users are searching for a way to change the local disk C to D, namely, moving OS from C drive to D drive so as to make D partition as the boot partition. For this purpose, you can apply the “Clone Partition” feature to clone C partition to D partition (note: this requires you to delete D partition to make it an unallocated space first of all).

Copy Partition


How to change primary hard drive in Windows 10/8/7 and the latest Windows 11? You can choose either of those two methods above. If you don’t want to reinstall OS and change startup disk, the second method is a better choice. Besides, AOMEI Partition Assistant Professional has many other advanced features: convert (system) disk between MBR and GPT without deleting partitions, extend NTFS system partition without reboot, split partitions and more. To change Server primary hard drive, you can use AOMEI Partition Assistant Server instead.