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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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2 Answers 2

Reset to default
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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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  • There's /sys/bus/pci/slots available on Linux 4.0.x, so it might be a type or has changed. However, there doesn't seem to be a power file by default.
    – Kalle Richter
    Jun 13, 2015 at 12:06
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    for me,turning off an AMD RX580, it was echo 1 > /sys/devices/pci0000:00/0000:00:01.0/remove
    – hanshenrik
    Feb 2, 2018 at 4:01
  • in my case (debian) # echo 1 > /sys/bus/pci/devices/0000\:01\:00.0/remove
    – Mochamad Arifin
    Jul 21, 2018 at 3:36
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    @hanshenrik this REMOVES the device from view in the OS, but does not change the P state on the actual device. Your device might still be on and consuming power, sometimes even more than when loading its driver.
    – istepaniuk
    Apr 4, 2021 at 12:15
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    Linux kernel documentation states explicitly that the sysfs pci 'remove' file "does not involve any kind of hot-plug functionality, e.g. powering off the device" kernel.org/doc/Documentation/filesystems/sysfs-pci.txt
    – ruief
    Nov 3, 2021 at 20:49
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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, 2010 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, 2010 at 3:20
  • What you want and what's possible won't always line up. Sorry.
    – Oli ♦
    Sep 23, 2010 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, 2010 at 13:53
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    If hardware can be turned of (not just disabled) by BIOS it means that any software can do the same - however this might mean low-level memory manipulation if it is not supported via the standard ACPI interface for doing those things - there is multiple kernel modules available for such things for HP and Asus machines - however they are not always bug free to say the least.
    – NiKiZe
    Dec 30, 2016 at 22:29

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