De acordo com esta postagem do Blog, você pode usar um ISO limpo e a configuração detectar sua chave OEM:
If you look at the bottom of my machine, you’ll notice there is no Windows 8 Certificate of Authenticity (COA). There is an official Windows 8 logo sticker, but no product key.
The good news is that you no longer have to worry about it fading or getting scratched. The 5x5 key is embedded in the BIOS. Therefore all I had to do in order to install a fresh clean copy of Windows 8 was attach an external DVD drive, boot from the retail DVD, and run setup. As soon as I connected to the internet, the machine activated. It never asked me for a key. No fuss!!!