How to perform a clean installation of Windows 8.1 Update
Process a clean installation of Windows 8.1 Update is as simple as installing or reinstalling previous versions of Windows 8. In other words, the process has not changed. First you need to prepare a bootable USB drive and then boot from it to start the installation. But if you are unsure how to prepare bootable media with Windows 8.1 Update, just follow the simple instructions below.
First, if you are going to perform a clean installation of Windows 8.1 Update by formatting the hard drive on which you installed your current version of Windows, you must create a backup of all important data stored on the same drive. So don’t forget to take care of this before installation. Second, to install you will need the product license key Windows 8.1. I assume you have it.
Preparing a bootable USB media to install Windows 8.1 Update
Bootable USB, you can create built-in Windows 7/8/8.1 (using command prompt), but we will use a free tool called Rufus, because most Windows users are not familiar with the command line and prefer to use software with simple GUI.
Step 1: connect the USB drive you want to use as bootable media, and do not forget to backup all important data stored on it, so in the process the drive will be formatted.
Step 2: Click on this link to download (free) Rufus. This tool works on all versions of Windows starting with XP.
Step 3: Run Rufus with administrator rights. To do this, click the right mouse button on the file Rufus.exe and then choose «Run as administrator».
Step 4: After running Rufus in the section «Device» choose your USB drive.
Step 5: Now, as the schema section select «MBR for BIOS or UEFI», but as file system choose FAT32, as a bootable USB formatted with NTFS can’t be used for installing Windows on UEFI-based computers. If you are sure that your computer without UEFI, choose NTFS, otherwise FAT32 will choose.
Step 6: Click on the small icon of CD/DVD and choose the ISO of Windows 8.1 Update.
Step 7: Now click «Start», and then, when you see the confirmation window to start preparation of a boot disk, click «OK».
Step 8: When bootable disk is ready, restart the computer and make changes to the BIOS/UEFI to allow booting from USB. Maybe your computer was already configured to boot from USB. In this case, to do nothing.
Step 9: Press any key when the screen displays the message «Press any key to boot from DVD…».
Step 10: When the screen displays the installation menu of Windows, choose language and click «Next» to continue installation.
Step 11: Next, click «Install».
Step 12: On the next screen you will need to enter the product key. Enter a valid 25-digit key, and then click «Next» to proceed to the next step.
Step 13: Accept the license agreement and click «Next». Then choose the custom installation type.
Step 14: Now choose the drive that needs to be installed Windows, format it (if required) and click «Next» to finally start the installation.
If the installation process of Windows 8.1 Update will cause you any trouble, read our guide «How to install Windows 8.1 RTM». There this process is described in more detail and accompanied by pictures.