Quite an old thread, but anyway, maybe this will help some on Win10.
Upgraded Asus X54HR from win7 to Win10. Worked like a charm on win 7.
After upgrade to Win 10, brightness does not work. When I bring it down, it does nothing, but screen goes black when going under 60%. Have to crank it up to get screen back on.
- Registry trick does not work (setting value to 0 in driver settings)
- uninstalling and re-installing drivers does not work.
- Disabling and re-enabling the display in device manager does nothing
BUT
If I uninstall ATK package from ASUS, I get screen brightness control back with the Fn key, but NOT in the notification area of windows 10, it still goes black under 60% but now, the first 2 steps DO decrease brightness. Let me say that again: works ok with Fn keys, *but* partially with Win10 notification control, without ATK package.
If I re-install old ATK package, problem re-appears! So this IS a *software* issue, and one that has been present for some time now. It's really A SHAME that no one at ASUS and/or AMD gives a s..... about it!