Instead of both having separate outputs, they both output exactly the same audio. They appear in the device manager as a single device called 'speakers' (see picture). Now, however, there's only one output, irrelevant of whether or not I have two outputs plugged in at the same time. This would give me two audio outputs in the device manager/sound list, which was pretty practical and enabled me to output different applications through the speakers or the headphones.

Now, here's my problem: when I was using Windows 7 on this same machine, I could plug headphones in the front panel connector, as well as speakers in the green back panel connector. To fix your computer no sound issue, you may want to update the ASUS Realtek audio driver. I have installed the latest realtek drivers R2.73 from the official website. ASUS Realtek Audio Driver Free Download for Windows 10, 7.

For a 5.1 audio system select 5.1 Speaker.

I have an Asus P8Z77-V LE PLUS motherboard, which includes a 'Realtek® ALC889 8-Channel High Definition Audio CODEC' onboard. In sound card application settings (Realtek HD Audio Manager, Realtek Audio Console): Speakers and headphones settings: Under Speaker Configuration select the number of speakers that you have. I'm having a little problem with my onboard audio, having just installed Windows 8.1 (clean install).

Asus realtek hd audio manager