Sorry not much help here, though I'm using onchip audio via IEC958 S/PDIF, in corepure64 lspci reports only "Intel Corporation 8 Series/C220 Series Chipset High Definition Audio Controller - Kernel driver in use: snd_hda_intel"
Alsa on the other hand lists the chip as "Realtek ALC1150" using alsamixer, you might try F6 to switch to your chip if supported..?
I'm using ALSA + Pulseaudio5 + paucontrol
with this command run at boot in xsession (otherwise no audio at all, and still alsa doesn't list the device even though it is apparently supported)
amixer -c 0 cset name='IEC958 Playback Switch' on (ensures S/PDIF is not muted on boot)
I think after all my failures to enable my audio chip in the end i simply removed all alsa commands from the backup and installed ALSA in core32 & corepure64 then simply allowed alsa to configure itself then installed/used the mixer to find the right volume control to enable, then installed Pulseaudio in core32 and pulseaudio5 in corepure64 + paucontrol
While this info might not be much help, I'd try alsamixer because you might be looking for a device which is identified differently.
try
https://wiki.archlinux.org/index.php/Alsa for some great alsa info
also
try
https://wiki.archlinux.org/index.php/ASUS_AT3IONT-I for more on your Realtek ALC887 device