If your PC is running slowly, you're experiencing frequent unexplained errors, or you just want to start using Windows 11 from scratch, the most effective and reliable solution is a clean install of Windows 11. Alternatively, if you want to repair your system without reinstalling it, an in-place upgrade is also very effective.
You may be worried that it might be difficult or that your data might be lost, but by following the correct steps, anyone can safely restore Windows 11 to its normal state.
This article will help you if you are considering installing Windows 11.
- "Clean install" to restore your PC to normal
- "Overwrite installation" to repair without reinstalling the OS
We will thoroughly explain these two methods, including screenshots, from the necessary preparations to specific steps and post-installation settings, so that even beginners will not get lost.
Should I choose a clean install or an overwrite install?
First, let's determine which installation method is best for you based on your goals and your PC's configuration.
| Features \ Types | Clean install | Overwrite installation (in-place upgrade) |
| Objective | Reset your PC and update your OS | Repair corrupted system files, fix OS issues, and update your Windows version |
| Data | All data on the C drive will be erased. | Apps and personal files are generally maintained |
| action | Become the most comfortable and stable | This will fix the issue, but the improvement will not be as dramatic as a clean install. |
| Acitivity Time | Long (including backup and reconfiguration) | Shorter (compared to a clean install) |
| Required Media | Bootable USB flash drive or ISO file | Bootable USB flash drive or ISO file |
| Recommended for times like this | When purchasing a PC, the PC runs too slowly, there are serious problems with unknown causes, and major OS upgrades | Frequent blue screens, corrupted system files, Windows Update failures, want to repair without reinstalling the OS |
The most important preparations before installation
Regardless of which installation method you choose, preparation beforehand is very important. Especially if you are doing a "clean install," backing up your data is essential.
1. Back up your important data (clean install required)
For a clean install, the C drive (the drive where Windows is installed)And all data that exists on the same physical drive as the C driveYour desktop, documents, downloads folder, photos, videos, and any other data you have stored on the same physical drive will be lost.
Be sure to back up any data you cannot afford to lose to an external hard drive, USB memory stick, or cloud storage.
- Author's recommendation: An external hard drive is useful for efficiently backing up large files.
[Advice] Choose a slightly larger capacity with an eye to the future! Considering the increasing number of photos, videos, and apps, we recommend choosing an external hard drive with the same or larger capacity as your PC's internal storage (e.g., 2TB or 4TB or more). Since you can use it for a long time once you purchase it, choosing a larger capacity, even if it means a slightly larger initial investment, will reduce the hassle and additional expenses of replacing it later.
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2. Create Windows 11 installation media
To install Windows 11, you'll need a bootable USB flash drive, burn the ISO file to a DVD, or mount it as a virtual drive.
The easiest and most recommended: This is how to create a bootable USB memory stick using the official Microsoft Media Creation Tool.
- How to Use the Windows 11 Media Creation Tool | Error Troubleshooting
- Complete steps to create a Windows 11 installation USB drive using Rufus
3. Check your product key (if necessary)
Typically, for branded PCs or PCs upgraded from Windows 10, the product key is tied to the motherboard, so you don't need to re-enter it. However, if you built your own PC or purchased the OS separately, you may need a product key.
- Confirmation method:
- The package or email you received at the time of purchase
4. Prepare drivers (especially for clean installs)
If you have an older PC, you may not be able to connect to the Internet or the screen may be distorted after a clean install because the network adapter or graphics card drivers are not installed.
Preparation Method: It is a good idea to download the latest LAN drivers and graphics drivers from your PC manufacturer's website to a USB memory stick beforehand.
Steps to clean install Windows 11
Let's go through each step to restore your PC to factory settings.
- If you are using a laptop, be sure to connect the power cord before proceeding.
- Disconnect any external devices connected to your PC (such as external hard drives) as they may interfere with the installation of Windows.
Step 1: Boot your PC from the installation media
Insert the created installation USB memory into your PC and start up the PC.
1. Turn on the PC and as soon as the manufacturer's logo appears, Key to call up the BIOS/UEFI settings screenPress repeatedly. (Example: Delkey,F2key,F10key,EscKeys, etc. Varies by manufacturer.)
2. In the BIOS/UEFI settings screen, find the "Boot" or "Startup" item and change the boot order so that the "USB flash drive" is first in the PC boot order.
3. Save the settings and restart your PC. Your PC will now boot from the USB memory.
4. When you see the message "Press any key to boot from CD or DVD...," press Enter. Windows 11 setup will then begin.
*Keys and item names may differ depending on the motherboard manufacturer. There is often an operation guide displayed at the bottom or right side of the screen, so please refer to that.
For reference, I have included the BIOS screen for my motherboard model number: B550M-P4.
Step 2: Proceed with Windows 11 setup
When the Windows 11 Setup screen appears, follow the on-screen instructions.
1.Language and other settings: Select "Japanese" and click "Next".
2.Select Keyboard Settings:The keyboard type is "Japanese keyboard (106/109 keys)” and click “Next”.
*By default, "PC/AT Extended Keyboard (101/102 keys)" is selected. If you select this, the keyboard layout will be in English.
3.Selecting Setup Options: Check "I agree to deleting everything, including files, apps, and settings (A)" and click "Next".
*If you do not check this box, the "Next" button will not be enabled.
Remember this!
Select "Repair your PC", click "Next", and then select "Microsoft IME" under "Choose your keyboard layout".Windows Recovery Environment (WinRE)will open and you can repair Windows, etc.
4.Enter your product key: If you have a product key, enter it. If you don't have one, even if you click "I don't have a product key," it will usually be automatically authenticated after connecting to the Internet.
5.Image (edition) selection: Select the edition of Windows 11 you want to install (Home/Pro, etc.) and click Next.
6.Acceptance of applicable notices and license terms: Click "Agree".
Step 3: Delete and format the partition (Important!)
This is the most important step in a clean install.This will erase all data on the C drive, so proceed with caution.
1.Choosing where to install Windows 11A list of drives will be displayed. If you have multiple physical drives, carefully check the "Disk X" (e.g. Disk 0) where you want to install Windows.
2. Select the "System," "MSR (Reserved)," and "Recovery" partitions on the physical drive where Windows is installed, as well as the "Primary" partition where Windows is installed (usually the C drive, which has the largest capacity), and click "Delete."
[Additional Information] What are these partitions? In the list of drives, you may see several small partitions such as "System," "MSR (Reserved)," and "Recovery." These are hidden partitions that have special functions that Windows needs to function properly.
- System partition: Contains files necessary for Windows to start up. It is usually very small (approximately 100MB to 500MB).
- MSR (Reserved) Partition: This partition is reserved for internal use by Windows. It is usually empty and is not directly used by the OS, but is reserved for future disk management operations. Its capacity is very small.
- Recovery partitionThis file contains data for troubleshooting Windows and restoring your PC to its factory settings. If your PC was manufactured by a PC manufacturer, this file may be particularly large.
The best thing to do is to make a complete backup of the data on your data partition, delete all partitions on "Disk X" (e.g. Disk 0) where you want to install Windows, and then perform a clean install.
[Important Note: If you want to keep the data partition]
If, in the same physical drive (e.g., Disk 0),If you have a partition you created to store personal files (e.g., a partition used as D drive) and want to keep that dataDo not delete the data partition.
However, if you install it this way, the partition where Windows is installed (C drive) will be clean,The remaining data partition will retain the data, settings, file access permissions, etc. created and used in the previous Windows environment..
This can lead to the following situations:
- Remnants of old software: If an application you used in your previous version of Windows wrote configuration files to the data partition, those files will remain.
- Permissions Issues: When you try to access files or folders in the remaining data partition in the new Windows environment, you may encounter permission issues such as "Access Denied."
- Malware risk: If your previous Windows environment was infected with malware, the malware may remain in the data on the data partition.
For this reason, the most recommended "ultimate clean install" is to carefully back up only the data you need from the data partition, then delete all partitions on the physical drive (e.g. Disk 0) and create new partitions from the "unallocated space."
This allows you to completely wipe the entire drive before installing Windows, and then restore the backed up data to the new environment, avoiding potential issues and creating an optimal, trouble-free environment.
3. After deleting, it will show "Unallocated Space on Disk 0". Select it and click "Create Partition" to create a new partition.
4. Click "Apply" and Windows will automatically create the necessary system partitions.
5. From the created partition,Select the largest partition, "Primary (1st)"Click "Next" to complete the installation preparation.
Recovery partitionis created automatically during a clean install. After a clean install,ディスクの管理You can check from.
Step 4: Installing and initializing Windows 11
Ready to install:Check the contents and click "Install" to start installing Windows 11.
From this point on, files will be copied automatically and the installation will proceed. Your PC will restart several times, so just wait.
1. Once the installation is complete, your PC will restart and the Windows 11 initial setup screen will appear. Click "Yes".
2. Set the keyboard layout, name of the device, etc.
3. Sign in with your Microsoft account or create a local account.
If you want to sign in with your Microsoft account, follow the on-screen instructions.
If you want to create a local account
If you want to create a local account,
1. On the "Add a Microsoft Account" screen, enter your email address "aaa@aaa.com" and click "Next."
2. On the next screen, click "Use a password instead."
3. Enter an appropriate password "1111111111" (e.g., 10 1s) in "Enter password" and click "Sign in."
4.Then, a message will appear saying "A problem has occurred," so just click "Next."
5. You will be asked "Who will use this device?" Enter your name (account name) and click "Next".
6. A password entry screen will appear. If no password is required, simply click "Next".
4. Check your device's privacy settings, etc., and proceed by clicking "Agree."
5. Please wait as the initial setup will be performed. Once the initial setup is complete, Windows 11 will start.
This completes the clean installation of Windows 11.
How to overwrite (repair) Windows 11
This is a useful method if you want to repair and update only the system files without reinstalling your current Windows 11 operating system. Your personal files and apps will remain intact.
- If you are using a laptop, be sure to connect the power cord before proceeding.
- Disconnect any external devices connected to your PC (such as external hard drives) as they may interfere with the installation of Windows.
- An internet connection is required to check for and download updates.
- Please do not perform any other operations while checking for or downloading updates, as this may cause the setup to freeze.
Step 1: Start setup from the installation media
Unlike a clean install, you'll start with Windows 11 running.
- Connect the created installation USB memory to your PC, or double-click the downloaded ISO file to mount it.
- Double-click "setup.exe" on the USB memory or in the ISO file to run it.
- If "User Account Control" appears, click "Yes".
- When the Windows 11 Setup screen appears, click Next.
How to download Windows 11 ISO files
Step 2: Download updates and choose installation type
1. The update check will begin, so please wait.
2.Accept the license terms international success.
3. It will check for updates again.
*Depending on the status of the update installation, this may take a very long time.
4.Choose your installation type: Make sure that "Keep personal files and apps" is selected (there is a check mark on the left). This is the key to overwrite installation.
If it is not displayed as an option, please check that the edition of Windows 11 on your PC matches the edition of the installation media you are using.
5. Click "Install" to start the overwrite installation.
Step 3: Complete the overwrite installation
Your PC will restart several times to complete the overwrite installation, most likely keeping your personal files and installed apps.
cleanPost-installation configuration and verification
Once the clean installation is complete, check the following settings to make your PC more comfortable and secure.
- Run Windows Update: Make sure you have the latest security updates and drivers.
- Installing device driversIf necessary, download and install the latest drivers from your PC manufacturer's website, especially graphics and chipset drivers.
- Restoring backup data: If you are performing a clean install, restore the backed up data to your PC.
- Reinstalling necessary apps: If it's a clean install, reinstall the apps you were using.
- Introduction of antivirus software: Don't forget to install and configure antivirus software.
- 復元ポイントの作成: When your system is working properly, it's a good idea to create a system restore point just in case.
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Summary
Performing a clean install or overwrite install of Windows 11 is not a difficult task. By following this complete guide and following each step carefully, anyone can safely restore their PC to normal operation.
- Clean install: When you want to reset your PC to a clean slate.Don't forget to make a backup.
- 上書きインストール: When your PC becomes unstable and you want to repair it without reinstalling the OS.
We hope this guide helps get your Windows 11 running smoothly and at its best again.
