Comment 31 for bug 1414706

No obvious difference (all coefs are the same!), but several things are differing, first, the product name:

-Product Name: 20AMOS3
+Product Name: 20AMZ02QUS

Second, even the hardware is of a later revision:

-00:1b.0 Audio device: Intel Corporation 8 Series HD Audio Controller (rev 03)
+00:1b.0 Audio device: Intel Corporation Lynx Point-LP HD Audio Controller (rev 04)

Second, firmware, kernel and ALSA dkms are all newer on the working one:

-Firmware Version: GIET53WW (2.01 )
+Firmware Version: GIET60WW (2.10 )

-Kernel release: 3.13.0-32-generic
+Kernel release: 3.13.0-46-generic

-[ 15.242582] snd_hda_intel 0000:00:1b.0: Probing card using HDA DKMS, version 0.201502151246~ubuntu14.04.1
+[ 13.866567] snd_hda_intel 0000:00:1b.0: Probing card using HDA DKMS, version 0.201503011031~ubuntu14.04.1

On the non-working one, please try updating both the firmware, the kernel, and the ALSA daily dkms on the non-working one to rule out differences between the non-working and working one.
Then post another alsa-info with dump_coef on. Thanks!