Comment 79 for bug 141445

shadowfoxx and Vijay, more playing around and I agree the VREF of 50 is the way to go. More good news, I have a way to make this persistent even with a reboot :). Obviously the end solution is to submit a patch to ALSA, which I will do eventually but thankfully there is an early patching system available which we can take advantage of, you can read about it at
http://kernel.org/pub/linux/kernel/people/tiwai/docs/HD-Audio.html#_early_patching

But here is the goods as you have to use hda-verb and sysfs to poke around to get the necessary values. Cut and paste the following into a new file '/lib/firmware/hda-init.fw'.

----snip----
[codec]
0x10ec0262 0x17aa3837 0

[verb]
0x19 0x707 0x21
----snip----

then modify your /etc/modprobe.d/alsa-base.conf file to add the following to the 'options snd-hda-intel' line 'patch=hda-init.fw'. So you should now have something like:
options snd-hda-intel power_save=10 power_save_controller=N model=lenovo-3000 patch=hda-init.fw

This will allow the VREF_50 to survive the reboot, works for me :). For some reason the input source keeps switching back to Mic and I have to change it to Int Mic using alsamixer each boot but I suspect this is fixable.