If you have a retail Windows 8 product key and want to clean install Windows 8.1 or Windows 8.1 Update, then you would need to enter a generic key below to install unactivated with, and change the product key later on in step 22 below to activate with your Windows 8 key. Generic keys to install with: Windows 8 (core): FB4WR-32NVD-4RW79-XQFWH-CYQG3 More @Wikipedia
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