What I would suggest is to avoid BIOS modding altogether and just install Windows 7 Ultimate in Legacy mode with a MBR (i.e. not UEFI mode with GPT) and then use Daz's Loader to activate it. Then do your Windows 10 Pro Upgrade and it will activate online and store a Hardware ID on Microsoft's servers. Then you can clean install Windows 10 Pro in UEFI mode (if you want to use fast-boot) and it will activate automatically when you are online. I have done this myself and can verify that it works.
@RADITZDJ Due to the design of Asus firmwares, once you enabled SLIC 2.1 you lose the abilities to toggle CSM & Fastboot. The MSDM table will remain though. It would be better to follow chinobino's advice.
Thank you chinobino; Tito So then I'll take chinobino's advice I already used Daz Loader to activate my PCBu Then upgrade to win 10 pro But not yet try to fresh install on the machine with Daz Case closed Thank you
Funy. Why you have to downgrade it to 7 instead of upgrade from 8.1 directly to 10? Just because of Pro or Home edition? I think that many functions of Pro edition are not necessary for most people.
Most of the bios that came with the windows 8.1 slp key, already have the slic 2.1 in the bios, check whit slic tookit , if the slic is there, you just need to use the multioem activator with windows 7 pro. Regards