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With the purchase of an Intel SSD and 85WHr Li-ion battery and the linking of wifi and bluetooth to my laptop's wireless switch, extensive Intel PowerTop usage, switching from compiz to metacity, stopping of the desktop-couch daemon, removal of Ubuntu One and several other services from my startup, disabling of everything possible in my BIOS, and physical removal of my optical drive, I've gotten my battery life up fairly high, but I think there's still more to be done. Specifically, when I'm in class taking notes, I want to temporarily but completely power down:

  • Ethernet
  • Firewire
  • USB ports
  • SD card reader
  • Optical drive
  • Webcam
  • Sound card
  • PCMCIA slot

..without turning them off in my BIOS like they are now, if possible, because then I have to restart my computer to use any of them. As it stands, I still haven't managed to power down:

Firewire USB connection to webcam sound card

How do I tell Linux to disable and power down these devices? Is it true that any PCI slot can be physically powered down?

My current idle power consumption is 7.9 watts plus the screen. (10.0W at min. brightness)

Also, how do I set the screen timeout to ten seconds? gconf editor isn't honoring it when I set it to that. Will switching from nVidia to Nouveau save any significant amount of power?

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All the settings are here askubuntu.com/questions/285434/… –  Qasim May 29 '13 at 2:48
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2 Answers

I could be wrong (if you think I am, just leave a comment) but I always thought that things that were plugged in (or soldered on, as is the case in most laptops) are always "on" and available unless disabled in the BIOS.

However most of these devices will only be using significant power when they're actively being used. The only real exception to this is wireless but you have a hardware switch for this. USB ports also power their plugees so you need to unplug USB things but that doesn't sound like an unreasonable request.

You can, of course, unload certain kernel modules which stops software having access to hardware but I doubt this would turn them off.

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You use the word 'significant' and 'reasonable' but in my case, 1.3 watts mean one whole hour of battery life. And I need that hour, so I need those 1.3 watts. –  ethana2 Sep 23 '10 at 1:59
    
With the other changes I've made, just 1 Watt is now more than 1 hour of battery life. –  ethana2 Sep 23 '10 at 3:20
    
What you want and what's possible won't always line up. Sorry. –  Oli Sep 23 '10 at 8:02
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If I can confirm that it is not physically possible I will stop pursuing it... but I'd prefer not to give up prematurely. Does the bios have access to hardware features that the operating system does not? –  ethana2 Sep 23 '10 at 13:53
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Try echo 0 > /sys/bus/pci/slot/$N/power for appropriate slot.

lspci -vv may help to identify the device. This is not very well documented...

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