Clean Install of Windows 10/11: Complete 2026 Guide

Introduction / Why This Is Needed

A clean Windows installation is the most effective way to restore your computer's original speed and stability. Unlike a system reset or targeted repair, this method removes all software junk, malware, conflicting drivers, and remnants of old programs. After completing this guide, you will have a "fresh" system running at peak performance. The process will take about an hour, but the result is worth it.

Requirements / Preparation

Before you begin, ensure you have:

1. Another computer or laptop to prepare the bootable USB drive (if installing on your main PC).
2. USB 3.0+ flash drive with a capacity of at least 8 GB (16 GB recommended). All data on it will be erased.
3. Stable internet connection to download the Windows image (size ~5-6 GB).
4. Windows product key (digital license or 25-character key). You can enter it later.
5. Backup of all important files from the system drive (usually C:\Users\Username\), including documents, images, browser bookmarks, and program keys. Verify the backup is accessible and not stored on the same system drive.
6. Network drivers (Ethernet/Wi-Fi), if your PC lacks a built-in network card driver included with Windows. Sometimes after a clean install, internet may not be available, which is critical for downloading other drivers. Download them from your motherboard/laptop manufacturer's website on another computer and transfer them to a separate USB drive in advance.

Step-by-Step Guide

Step 1: Creating a Bootable USB Flash Drive with Windows

The most reliable method is to use Microsoft's official tool.

1. On the working computer, open your browser and go to the Media Creation Tool page (for Windows 11) or the Media Creation Tool page (for Windows 10).
2. Download and run MediaCreationTool.exe. Accept the license agreement.
3. Select 'Create installation media (USB flash drive, DVD, or ISO file) for another PC' and click 'Next'.
4. Ensure the correct settings are selected: Language, Edition (Windows 10/11), and Architecture (usually 'Both' or matching your x64 architecture). Click 'Next'.
5. Insert the prepared USB drive. Select it from the list and click 'Next'. The tool will automatically format the drive to FAT32 and copy all necessary files. This process takes 10-20 minutes.

Step 2: Configuring Boot from USB (BIOS/UEFI)

Now you need to make the PC boot from the USB device instead of the hard drive.

1. Insert the prepared USB drive into a USB 2.0/3.0 port on the target computer.
2. Turn on or restart the computer.
3. Immediately after powering on, start pressing the key to enter BIOS/UEFI or the boot menu. Common keys: Del, F2, F10, F12, Esc. The exact key is usually displayed on the screen during boot (e.g., 'Press F12 for Boot Menu').
4. If you entered the boot menu, simply select your USB drive (it may be labeled UEFI: USB... or USB-HDD) and press Enter.
5. If you entered the full BIOS/UEFI (usually a blue or black interface), find the Boot or Загрузка section. In the Boot Option Priorities list, move your USB drive to the first position using +/- or arrow keys. Then find the Secure Boot option and disable it (set to Disabled). For Windows 11 installation, you may also need to enable TPM 2.0 and Virtualization (VT-x/AMD-V) in the security settings. Save changes and exit (key F10).

Step 3: Running the Installer and Disk Partitioning

After successfully booting from the USB drive, the first Windows installer screen will appear.

1. Select your language, time format, and keyboard layout. Click 'Next'.
2. Click 'Install now'.
3. Product key entry. If you have a key, enter it. If the key is tied to an account or you want to activate later, click 'I don't have a product key'. Select the desired Windows version (Pro/Home) on the next screen.
4. Accept the license agreement.
5. Select the installation type: 'Custom: install Windows only (for advanced users)'.
6. You will reach the disk selection screen. This is the most critical step.

Step 4: Formatting the System Drive (Critically Important Step)

On this screen, you see a list of physical disks and their partitions.

1. Identify which disk/partition you are installing Windows to. Usually it's the largest disk (Disk 0). All data on this drive will be erased.
2. Delete all existing partitions on the target drive. To do this, sequentially select each partition (e.g., 'Partition 1', 'Partition 2', 'System Reserved', 'Primary') and click the 'Delete' button. Repeat for all partitions on that drive. After deleting all partitions, you will see a single line of 'Unallocated Space' equal to the full size of the drive.
3. Select this unallocated space and click 'Next'. The Windows installer will automatically create the necessary system partitions (EFI, MSR, primary) in the correct order and format. Do not create partitions manually unless you are 100% sure.

⚠️ Important: If you want to keep data on another drive (e.g., D:), ensure you are formatting only the system drive (usually Disk 0). Do not delete partitions on other physical drives.

Step 5: Waiting for Installation and Initial Setup

1. The installer will begin copying files, installing components, and applying updates. This process takes 15-40 minutes depending on the media speed and PC. The computer will restart several times. Do not remove the USB drive until the OOBE (Out-of-Box Experience) setup screen appears.
2. After restarts, you will reach the 'Welcome' screen (Out-of-Box Experience). Here you configure initial settings:
   • Region and keyboard layout.
   • Network connection (Wi-Fi/Ethernet). Internet connection is important for subsequent activation and driver downloads.
   • Account setup. We recommend creating a local account (click 'Offline account' or 'Limited access'), to avoid internet binding at this stage. You can set a password later.
   • Privacy settings. Carefully disable everything related to sending diagnostic data, advertising, location, and advertising ID.
3. Complete the setup. After signing in, the desktop will appear.

Step 6: Installing Drivers and Updates

The system is installed but not yet ready for use.

1. Windows Updates. Open 'Settings' (Win + I) → 'Update & Security' (Windows 10) or 'Windows Update' (Windows 11). Click 'Check for updates'. Install all available updates, including optional ones and drivers. This may require several restarts.
2. Install hardware drivers.
   • Network driver: If you still have no internet after updates, download the network card driver (Ethernet/Wi-Fi) from your PC/motherboard manufacturer's website on another computer and transfer it to a USB drive. Install it manually via 'Device Manager'.
   • Chipset, graphics, sound drivers: Visit the official website of your laptop manufacturer (Dell, HP, Lenovo, ASUS, etc.) or motherboard manufacturer (for a custom PC). In the 'Support' or 'Downloads' section, find your model and download the latest drivers for Windows 10/11. Install them manually, starting with the chipset, then graphics, sound, and others.
   • Alternative: You can use utilities like Driver Booster or Snappy Driver Installer, but they sometimes offer suboptimal or outdated versions. The manual method is more reliable.

Checking the Result

The installation is successful if:

1. The system boots from the system drive (SSD/HDD), not the USB drive.
2. There are no errors or warnings on the desktop.
3. In 'Device Manager' (devmgmt.msc), there are no devices with a yellow exclamation mark (except possibly unknown devices without drivers).
4. 'Control Panel' → 'System' shows correct Windows activation ('Windows is activated').
5. Internet access and sound playback work.
6. Press Win + R, type winver, and press Enter. Verify the correct Windows version and build are displayed.

Potential Issues

• Computer does not boot from USB: Check the boot order in BIOS/UEFI. Ensure the USB drive was created in the correct mode (UEFI or Legacy). For modern Windows 11, UEFI mode with Secure Boot disabled (temporarily) is almost always required. The Media Creation Tool typically creates a compatible drive.
• Error 'Windows cannot find the installation image' or freezing on the logo: There may be an issue with the media. Recreate the USB drive using a different USB port (preferably USB 2.0) or a different flash drive. Verify the image integrity via the SHA-1 checksum on the Microsoft website.
• No internet after installation: Install the network card driver manually from the USB drive (see Step 6). This is often the driver for Realtek PCIe GbE Family Controller (wired) or Intel/Realtek Wireless-AC (Wi-Fi).
• Windows does not activate: If you skipped key entry, go to 'Settings' → 'Update & Security' → 'Activation'. Click 'Change product key' and enter your key. For a digital license, ensure the computer is connected to the internet and you are signed in to the Microsoft account it's linked to.
• Missing drivers for the graphics card (NVIDIA/AMD/Intel): Download the driver from the official graphics card manufacturer's website, not the laptop manufacturer's site. Select the exact model and Windows version.
• Error 'Not enough space to create partitions': The target disk has an MBR partition table, but the system requires GPT for UEFI boot. In the disk selection screen, press Shift + F10 to open the command prompt. Type diskpart, then list disk, then select disk X (where X is your system disk number), then clean. This will completely wipe the disk and convert it to GPT. Close the command prompt and refresh the disk list in the installer. All data on the disk will be destroyed!