Windows 8.1 Update has finally been released via Windows Update to all existing Windows 8.1 users and is a mandatory update. PC users who’re running Windows 8.1 can now get the major Update either via Windows Update or by manually downloading the same. As you likely know, this is a free update to Windows 8.1 and is designed to fix many announces that keyboard and mouse users were experiencing while using Windows 8.1. In addition to new features and tweaks, there are a number of improvements under the hood as well. Because of this reason, many users want to perform a clean install of Windows 8.1 Update to get the most of out of the newest version of Windows. Performing a clean install of Windows 8.1 Update is as simple as installing or reinstalling previous versions of Windows. You just need to prepare a bootable USB/DVD and then boot from the bootable media to begin the installation. This method is also helpful when your PC is unbootable (see how to backup data from unbootable PC) or you want to install Windows 8.1 Update on a newly assembled computer. But if you’re not sure how to prepare a bootable USB drive of Windows 8.1 Update, simply follow the given below instructions to easily create bootable USB of Windows 8.1 Update and then clean install Windows 8.1 Update from the USB drive. If you’re going to perform a clean install of Windows 8.1 Update by formatting your existing Windows 8.1 drive, you need to back up all data before beginning to install Windows 8.1 Update. Backup all data to an external hard drive or another drive on the same PC. More importantly, you must have your Windows 8.1 product key in order to perform a clean installation. If you can’t locate the product key, please refer to our how to recover Windows 8/8.1 product key or how to recover the product key from unbootable PC guide to easily retrieve the product key. Preparing Windows 8.1 Update bootable USB While it’s possible to create a bootable USB of Windows 8.1 Update with the help of Command Prompt (see how to install Windows 7/8/8.1 from USB drive to see the Command Prompt method), we’re going to use a free tool named Rufus to prepare the bootable USB, as most Windows users aren’t familiar with the Command Prompt and prefer using software with easy-to-use interface. Step 1: Connect a USB drive that you would like to use as bootable media to clean install Windows 8.1 Update, and be sure to backup all data to a safer location as we need to format the drive in order to make it bootable. However, you can follow our how to create bootable USB without formatting the drive to prepare the drive without having to erase the data. Step 2: Visit this page of Rufus (free) and download the software on a working PC. You can run Rufus on a PC running Windows XP or higher version of Windows. Step 3: Run the tool with admin rights. To do that, right-click on Rufus.exe file and then click Run as administrator option. Click on the Yes button when you see the UAC dialog. Step 4: Once Rufus is running, under Device section, select your USB drive. Step 5: Next, select your partition scheme as MBR partition scheme for BIOS or UEFI computers and select the File system as FAT32, as a bootable USB formatted with NTFS can’t be used to install Windows on a UEFI based computer. However, if you’re sure that your PC is not a UEFI PC, you can simply select NTFS as the File system. But if your PC is UEFI, be sure to select FAT32. Step 6: Click the small CD/DVD icon next to ISO image button to browse to your Windows 8.1 Update ISO image file and select the same. Step 7: Finally, click the Start button and then click OK button when you see the confirmation box to begin preparing your Windows 8.1 Update bootable USB. Step 8: Once your bootable USB is ready, restart your PC, make necessary changes to BIOS/UEFI settings to enable booting from USB. Step 9: Press any key when you see Press any key to boot from DVD… message on the screen. Step 10: When you see Install Windows screen, select your language, keyboard and then click Next button to continue. Step 11: In the next screen, click Install Windows button. Step 12: When you’re asked to enter the product key, enter a valid 25-character product key and then click Next button to proceed to the next step. Step 13: On Where do you want to install Windows screen, select your Windows 8.1 drive or any other drive on which you want to install Windows, format the drive (if required), and finally, click Install button to begin installing Windows. Step 14: From here onwards, you can follow the extremely easy on-screen instructions to sign in with Microsoft account and complete the installation.