I do not use Gnome. Its quite possible you have a problem with your Gnome mixer, in which case I can not help.
Thanks for that. I see you have an ALC888 and 1.0.16 of alsa.
Searching for the alc888 on the alsa project web site I get this: Search results for 1.0.16 - AlsaProject
which indicates there are a number of updates to alsa available since 1.0.16 of alsa.
But before jumping to recommend an update, I also note that you have WAY TOO MANY pulse and alsa apps installed. Surely those were not installed by default ?
Linux is not like Windows. In general, in Linux, installing extra apps is not a good idea, especially if one does not know what one is doing. AND if one decides to go ahead anyway and install extra apps, it is good idea to make note of what one installed, so one can remove it later if it does no good. I have no idea why you installed the various apps, nor what is needed for what, so I can not help you clean that app. But its messy. Very messy. And that can lead to problems.
Anway, it is possible you “might” be able to clear up your problem by assigning a model option that will be recognized by your 1.0.16 alsa version driver. I noted this for the ALSA-Configuration.txt file for 1.0.16 of alsa for the ALC888 (which you have on your PC):
3stack-dig 3-jack with SPDIF I/O
6stack-dig 6-jack digital with SPDIF I/O
3stack-6ch 3-jack 6-channel
3stack-6ch-dig 3-jack 6-channel with SPDIF I/O
6stack-dig-demo 6-jack digital for Intel demo board
acer Acer laptops (Travelmate 3012WTMi, Aspire 5600, etc)
acer-aspire Acer Aspire 9810
medion Medion Laptops
medion-md2 Medion MD2
targa-2ch-dig Targs/MSI with 2-channel
laptop-eapd 3-jack with SPDIF I/O and EAPD (Clevo M540JE, M550JE)
lenovo-101e Lenovo 101E
lenovo-nb0763 Lenovo NB0763
lenovo-ms7195-dig Lenovo MS7195
haier-w66 Haier W66
6stack-hp HP machines with 6stack (Nettle boards)
3stack-hp HP machines with 3stack (Lucknow, Samba boards)
6stack-dell Dell machines with 6stack (Inspiron 530)
mitac Mitac 8252D
auto auto-config reading BIOS (default)
So for your acer5920G, you could try to edit your /etc/modprobe.d/sound file, and add an extra line at the end and change it to:
options snd slots=snd-hda-intel
# u1Nb.6t3NVH6gP_8:82801H (ICH8 Family) HD Audio Controller
alias snd-card-0 snd-hda-intel
options snd-hda-intel model=acer
and the restart your alsa sound driver with: su -c ‘rcalsasound restart’ and enter root password when prompted. Then start your mixer again and check your ability to control your sound volume.
If that does not work, you could try acer-aspire instead. Restart alsa … test … etc … or try any one of the many other models until you find one that works.
Failing that, you could try to update your alsa, and if you get to that stage, let me know and I can point you to a guide on installing some already compiled rpms of the latest alsa version (for openSUSE).