I have 5.1 speaker set, also in ASUS Strix driver panel and also in Windows audio settings the layout is set to 5.1
But some games and some software for unknown reason detect the system as 7.1.
I don't remember the exact game titles - it's those games that have audio settings auto-detected from Windows and these games do not allow to change the speaker layout manually in the settings. They think that I have 7.1 so I miss some of the sounds that are supposed to come from side speakers (that I of course don't have because I have 5.1, not 7.1).
The software that also has the same problem is PowerDVD Ultra 15. You can manually set the correct number of speakers there but it's strange that it does not detect it rightly automatically. Auto detection thinks that I have 7.1. But sometimes it DOES detect the layout correctly (as 5.1). It is a bit of a problem because I often change from 5.1 to stereo headphones and I don't want to go to the PowerDVD settings every time I do this.