Any time you are asking for help on forum like this remember to include your system specifications particularly the motherboard make and model, the realtek codec version it uses, your operating system and how you will use the audio (analog speakers or spdif optical output, etc)
Since we know nothing about your system its impossible to know what might be the issue. I have an older ALC892 codec board and while I believe it had 7.1 support its only really outputing at 5.1 because I have a 5.1 stereo setup.
***Breaking news! This is unbelievable to me. Asus no longer has a support page for the P9X79 LE or any X79 motherboard that runs Windows 10. Sure they added Win10 support late but its still totally viable. Its viable but its has issues. I guess Asus expects people to just not use it anymore but that seems terribly contradictory for a company that sells itself on quality components that last a long time. I may upgrade but this year to a more gaming focused machine but I still intend to use this a server. If someone found one of these dead or bought it on the cheap all it likely needs is a bios update. No more driver support or bios downloads at all!? WTF Asus? I have been buying them for over twenty years. This is lame and its going to be hard to buy another Asus. I will definitely take suggestions for a better manufacturer to support.
Missing links:
www.asus.com
www.asus.com
I have the ALC892. I have never gotten the sonic studio to work. Atmos worked but it didn't seem to add anything. Nahaimic may have worked but it was installed unintentionally and seems to draw more resources I would rather having for gaming. Soundblaster will run 720 suite sometimes for a few days but inevitably it figures out something is missing and the KGA config does not work at all for me (not entirely sure how to use it) What i run and has proven reliable for both analog output (headphones) and SPDIF is to install Alan's STANDARD drivers:
When installing I use this sequence. I have tested this many times your experience may be different. When you run installer first question is whether or not to install Intel bus driver I choose NO. Windows configurations I allow everything but remote desktop. I have no idea why anyone would allow a blind link to remote desktop that could be abused easily. I select Realtek APO with DTS/DDLL. You must deselect A-volute, Atmos and other options or it will install all of them. I dont know why they are all set to install by default since youshould probably just use one at a time. Sometimes I choose soundblaster just to use the recon mode as it does help with directional sound and positioning cues in FPS games. Eventually I will buy a creative card but that is not a option now. After rebooting its necessary to config the audio jack alerts and allow simultaneous outputs and input as well as set default communication devices accordingly. In the sound properties I disable all enhancements and choose 5.1 DTS option for the spdif optical output as well as optional frequencies. I also deselect the "allow exclusive control" as it can cause issues switching back and forth or using multiple apps with sound at the same time. Good luck. My system sounds phenomenal. But that took untold hours of trial and error.