By Michael / Last Updated October 30, 2020


How to replace my small system drive with larger one?

I have a small hard drive for my main system drive “C”, and I want to replace it with a larger one but keep Windows 10 operating system. Thanks.

- Question from

Why need to replace C Drive?

Generally, we install operating system on the C drive, so it is a lot more important to keep it functioning well than other drives. But there are 3 circumstances where you need to consider replacing the small C drive.

● The C drive is too small to keep the PC running smoothly. C/system drive needs some free space to maintain its running. If your C drive is out of space, the Windows running speed will slow down and ask you to clean the disk.
● Upgrade the internal disk to larger one. To have better experience, you may want to change their HDD with new SSD, meanwhile, you need to keep the same system environment, you can find a way to replace the system drive.

How to replace smaller C drive with SSD/HDD in Windows 10, 8, 7?

Step 1. Choose a correct SSD/HDD

Solid-state drive (SSD) is better than hard drive disk(HDD) to keep the operating system. Because SSDs use flash memory to write and read data give its much faster running speed than the traditional HDD. And they are more durable and safer to store system files and to run programs.

However, given the price of SSDs is higher than HDD’s, you can also choose a larger HDD. Whatever drive you would like to select, first of all, you need to make sure the size of the SSD has enough space to contain all the C drive data and information. For example, if you have a 400GB C drive, preferably, a drive with about 800GB, 1TB would be great.

And another thing you need to consider is interface for SSD. Interface standards of SSD include M. 2, PCIe, SATA, which provide different performance. And get to know what type of SSD your PC supports. If you want a M.2 drive, there should be M.2 slot on the motherboard.

Step 2. Clone hard drive or C drive to SSD/HDD

Cloning process is a convenient operation to transfer system, data, applications, settings to a new storage device. To replace small C drive, you don’t want to reinstall system and applications, because it takes time and energy.

Here we recommend cloning freeware named AOMEI Partition Assistant Standard, which helps you to copy a hard drive to another SSD/HDD in Windows 10, 8, 7. And there are 4 reasons why it is recommended to replace a small C drive.

● It supports all most Windows operating systems, like Windows 10, 8, 7, XP, Vista.
● It offers clone system partition or the whole disk functions, which give the choose to only replace the C drive or migrate the whole disk, including OS and other software and data.
● It supports cloning larger disk to smaller SSD. On account of high price of SSD, the source disk probably is bigger than your SSD. AOMEI Partition Assistant can clone successfully in this circumstance.

Download Freeware Win 10/8.1/8/7/XP
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    ✍Before cloning process, you need to make some preparations:

  • Get an adapter. you might need an adapter to connect the SSD with your PC when cloning.

  • Back up files the destination SSD if it is not new. The cloning operation will format the SSD that will delete all file on the SSD.

  • Install AOMEI Partition Assistant on your PC.

Step 1. Launch AOMEI Partition Assistant, click “Migrate OS to SSD”.

Step 2. Choose the SSD as the target SSD. If there is no unallocated space on it, you will need to delete partition on the SSD, and click “Next”.

Step 3. Edit partition on the destination disk, and click “Next”.

Step 4. Read the boot note and remember it, and click "Finish".

Step 4. Then, click “Apply” on the main interface to check the operation details. And click “Proceed” to commit it.


Step 5. Put out the old hard drive from the disk bay and place the cloned SSD on it.


With AOMEI Partition Assistant, you can easily replace small C drive with SSD or HDD in Windows 10, 8, 7. The “migrate OS to SSD” option only move the system partition and related data to the destination disk. If you want to migrate your other personal data, files, photos, games, please use the “Clone Disk Wizard” feature.

And it is work in most Windows operating system, like Windows 10, 8, 7, and Windows XP, Windows Vista. If you are using Windows Server system, the Server version can help you.