Although the above question might have answered your question, I still want to answer as this well cover every version of windows 8, 8.1 and 10. All these os lack something, the legacy boot menu which prevents the windows to be downgraded. What you need to do is to enable it.
To do it open task manager,
file->open and type cmd, and also check the option to run program as administrator.
Then in command prompt type:
" bcdedit /set {default} bootmenupolicy legacy " without the quotes and it will enable the legacy boot menu, which will let you open the menu when you used to mash F8 button several times while the PC boots up to get into safe move.
After doing this just put a windows 7 DVD, and install as usual. This does not require the windows to be of pro version, or having the same windows version. So you can install windows 7 ultimate on windows 10 home version, or whichever you like.
2for new devices you probably have driver issues. Look if ASUS still provides all drivers – magicandre1981 – 2015-12-13T07:35:38.320