What You Need Before You Start
You need three things: a USB drive with at least 8GB of storage, access to another working computer to create the bootable drive, and a Windows licence key. If you do not have the key yet, you can still install Windows and skip activation for now. The OS will run with some minor restrictions until you activate it, but nothing that stops you from getting set up and testing the build.
The USB drive will be completely wiped when you prepare it, so make sure there is nothing on it you want to keep. Any drive will work, including old flash drives sitting in a drawer. Speed helps a little during installation but is not a significant factor. As long as the drive holds 8GB and works, it is fine.
Make sure your new build is fully assembled with all drives connected and the monitor, keyboard, and mouse plugged in. You should have already confirmed the build posts correctly before reaching this step. If you have not confirmed that yet, do that first. Installing Windows onto a build that has hardware issues just makes the troubleshooting harder later.
Creating the Bootable USB Drive
On your working computer, go to Microsoft's website and download the Media Creation Tool. This is the official utility for creating a Windows installation drive. The download is free regardless of whether you have a licence key. The key only matters for activation after installation, not for downloading or installing the software itself.
Run the Media Creation Tool and choose the option to create installation media for another PC. Select your preferred language, the Windows edition you want (Home or Pro, usually Home for gaming builds), and 64-bit architecture. The tool will then download the necessary files and write them to your USB drive automatically.
This process takes between 20 and 45 minutes depending on your internet speed, since it needs to download several gigabytes of installation files. Do not interrupt it once it starts. When it finishes, you will have a bootable Windows installation drive ready to use.
If you do not have access to another Windows computer, there are alternative tools that can create a bootable drive from a downloaded ISO file. The process is slightly different but the end result is the same: a USB drive that your new PC can boot from.
Getting Into BIOS and Setting the Boot Order
Plug the USB drive into your new PC, then power it on. As soon as the screen shows any activity, press the key that opens your BIOS. This is usually Delete or F2, though some motherboards use F10 or F12. If you miss it, restart and try again. The timing is tight on modern hardware because POST completes so quickly.
Once you are in the BIOS, you need to make sure the system will boot from the USB drive rather than trying to load from an empty hard drive. Look for a Boot menu or Boot Priority section. You want to move your USB drive to the top of the boot order, above your main storage drive. The exact menu layout varies by motherboard manufacturer, but the concept is the same everywhere.
While you are in the BIOS, also check that your storage drive is visible. If you installed an NVMe drive, it should appear in the list of detected storage devices. If it is not showing up, the drive may not be seated properly in the M.2 slot. Check the connection before continuing.
Save your BIOS changes and exit. The system will reboot, and this time it should start loading from the USB drive rather than looking for an operating system that does not exist yet.
Walking Through the Windows Installer
The Windows installation screen will appear after a short loading phase. Select your language, time format, and keyboard layout, then click through to the install option. When prompted for a product key, you can enter it here or choose to skip it for now and activate later.
Select the edition of Windows that matches your licence, accept the terms, and choose the Custom install option rather than the Upgrade option. Custom install is what you want for a fresh build. The Upgrade path is for upgrading an existing installation and will not work correctly here.
The installer will show you all detected drives and partitions. On a brand new drive with nothing on it, you will see unallocated space. Click on that unallocated space and then click Next. The installer will create the necessary partitions automatically. You do not need to manually create or format partitions for a standard single-drive gaming build.
If you have multiple drives, be careful to select the correct one as the installation target. The installer will show the size of each drive to help you identify them. Install Windows only to the drive you want as your primary system drive, usually the fastest one you have.
The installation process then runs on its own. Your PC will restart several times during this process. Leave the USB drive plugged in, but the installer will boot from the drive automatically on the first restart after the initial file copy. After that, it will boot from your newly installed Windows. The whole process takes between 10 and 30 minutes.
Setting Up Windows for the First Time
After the last restart, Windows will walk you through initial setup. Choose your region, keyboard layout, and whether you want to connect to a network. For a gaming build, you can skip the network connection step during setup and handle it afterward, though some setup screens will push back on this a bit.
Windows will ask whether you want to set up the PC for personal use or for an organisation. Choose personal use. It will then ask you to sign in with a Microsoft account. You can create one if you do not have one, or on some versions you can skip account sign-in by looking for the option to set up a local account instead.
Work through the privacy settings screens. Most of the optional data sharing options can be turned off if you prefer. None of these settings affect performance. Once you reach the desktop, the operating system is installed and running. The next step is getting the right software and drivers onto the machine.
Activating Windows
If you skipped activation during installation, go to Settings and find the Activation section. Enter your product key there. Activation requires an internet connection and is usually instant once the key is entered.
If Windows does not activate and gives you an error, check that the key matches the edition you installed. A key for the Home edition will not activate a Pro installation, and vice versa. If the key was previously used on a different PC, you may need to use the phone activation method or contact Microsoft support to transfer the licence.
An unactivated Windows installation shows a watermark on the desktop and locks some personalisation settings, but it runs normally otherwise. If you are still sourcing a key, you can continue setting up the rest of the machine and activate later with no impact on how the PC performs.
What to Install Before Anything Else
Once Windows is up, resist the urge to immediately install your games. The right order matters here and skipping it leads to problems later.
First: Install your motherboard chipset drivers. These come on a disc with the board or are available as a download from the motherboard manufacturer's support page. Chipset drivers ensure your CPU, RAM, and storage devices communicate with the motherboard correctly.
Second: Install your GPU drivers. Download the latest version from your GPU manufacturer's website, not from a third-party driver aggregator. Run the installer, accept the recommended clean install option, and let it do its thing. Your resolution and refresh rate may be wrong until this step is done.
Third: Run Windows Update and let it complete fully. This can take a while on a fresh install and may require a few restarts. Do not skip it. Windows updates include security patches and often additional driver updates for hardware that Windows handles natively.
Fourth: Enable XMP or EXPO in the BIOS if your RAM supports it. This is a separate step from the install process but is easy to forget. Your RAM is running at its base speed until you enable this setting, which means you are not getting the performance you paid for. Go back into BIOS, find the memory profile setting, and enable it.
After that, your build is ready. Install your games, set up any additional software you need, and run a stress test to confirm everything is stable under load. A fresh install that passes a 30-minute CPU and GPU stress test is a build you can trust.