If you have a Windows 8.1 sticker on the side of your PC, you can use that key. However, if your PC came with Windows 8 (not 8.1) pre-installed, the key embedded in your motherboard's BIOS will work with a generic Windows 8.1 installer.
Download this directly from the Microsoft Software Download page . windows 8.1 installation media creation tool
Using the media creation tool for a "clean install" is often better than a simple upgrade. A clean install wipes the hard drive and installs a fresh copy of Windows 8.1, which eliminates: Bloatware from manufacturers. Accumulated system errors or registry issues. Persistent malware or viruses that survive standard scans. Important Note on Support If you have a Windows 8
USB Flash Drive: The tool will format your drive and turn it into a bootable installer. Using the media creation tool for a "clean
Locate the downloaded file (usually named WindowsSetup9Box.exe or similar) and double-click to run it. You may be prompted for administrator permission.
Download and Finalize: The tool will begin downloading the files. This can take anywhere from ten minutes to an hour depending on your internet speed. Once finished, the tool will verify the files and alert you when the media is ready. Why Use a Clean Installation?
This utility is a small executable file that automates the process of downloading the Windows 8.1 ISO file and burning it to a DVD or flash drive. Unlike third-party downloaders, this tool connects directly to Microsoft’s servers, ensuring that the version of Windows you receive is genuine, malware-free, and up to date.