Hello, I used PIDKey (by Ratiborus) in order to check the Edition Type of my Windows 8.1 key. Here's what I got: Description : Win 8.1 RTM Professional OEMM Edition ID : Professional Sub Type : [Blue]X18-95456 License Type : OEMM Channel : OEM Then I tried installing "Windows 8.1 Pro (Professional)" from the sticky thread "Windows 8.1 with Update ESDs Repository". I installed it using a generic key, then uninstalled the generic key using slmgr /upk, and finally tried using my key using the slui 3 command. However, it said that the product key doesn't match that version of Windows... So... which ISO version should be used? (perhaps the RTM version? couldn't find any recent ones...) Thanks in advance. Edit: well,using the first listed version in "Windows 8.1 x86/x64 ISO Download ALL VERSION/LANG [HTTP-links] " worked... feeling quite stupid right now