Power Management

When a computer is powered on but is idle and not being used, the computer is using more power than it needs to. A computer that is idle for extended periods of time can be placed into a reduced power state called standby, sometimes known as sleep. When a modern computer is placed in standby it uses about the same power as when it's turned off which is between 4 to 25 times less power compared to when it is powered on and idle.

Potential Savings - Based on the results of the proof-of-concept, it was determined that BigFix’s power management features had the potential to save the University between $25 and $60 per machine per year by placing machines into standby when not in use. By placing Cooperative Lab Management's 5,300 computers into standby when they are not in use, we can save the university $56 per computer per year, for a yearly savings of $296,800.

BigFix Power Management

BigFix is able to set the power management settings for Windows and Mac clients while also addressing some limitations of the OS. Power settings can be configured and applied through the BigFix management console. The BigFix agent can also monitor a system for idle usage and estimate the potential power savings by applying power-saving settings.

With BigFix there are three ways of waking sleeping machines:

  • Wake on LAN - BigFix can enable Wake on LAN for systems that have support for the standard in hardware. Wake on LAN packets are broadcast packets that cannot go beyond a physical network. BigFix's Wake on LAN support includes an important feature, called Last Man Standing, that allows administrators to designate one or more machines per network to act as Wake on LAN relays. These machines are used by the central BigFix server to wake sleeping machines by having the local Last Man Standing machine send the Wake on LAN packet to it.
  • Self Wake - The BigFix agent has the ability at the client to wake itself up at a given time that is set by an administrator through a BigFix Task or Fixlet.
  • Wake on Touch - BigFix can set a client so that the mouse and keyboard can be used to wake a sleeping machine.

Additional BigFix Tools

  • Power Footprint Dashboard - Allows IT staff to show their users the potential power and carbon savings of setting aggressive power settings on a given computer.
  • The Penn State User Decided Power Management Program - Allows IT staff to empower their end users with the ability to decide what power settings should be applied to their computer and to change those settings whenever necessary.

Observed Hardware Power Usage

To help understand the amount of power consumed by specific computer hardware, the amount of power consumed by common computer hardware in its various states of operation was measured.  All data listed below was gathered by using a quality digital wattmeter.

Model At Rest (S0) Standby/Sleep (S3) Hibernation (S4)
or Powered off
Dell 1707 LCD Monitor .20 amps <.01 amps N/A
Apple 23" Display .23 amps .03 amps N/A
Dell Optiplex 270 .83 amps .64 amps .05 amps
Dell Optiplex 280 1.14 amps .09 amps .08 amps
Dell Optiplex 620 (D) 1.16 amps .08 amps .06 amps
Dell Optiplex 620 (HT) .88 amps .09 amps .08 amps
Dell Optiplex 745 1.03 amps .07 amps .06 amps
Dell Optiplex 755 .46 amps .11 amps .11 amps
Dell Optiplex 760 .38 amps .10 amps .09 amps
Dell Optiplex 790 .21 amps .06 amps <.01 amps
Dell Optiplex 960 .42 amps .08 amps .06 amps
Dell Optiplex 980 .24 amps .02 amps <.01 amps
Dell Optiplex 990 .18 amps .01 amps <.01 amps
Apple Mac Mini (Late 2006) 25 amps .08 amps  
Apple Mac Mini (Early 2009) 25 amps .03 amps  
Apple iMac 20" (Intel) .58 amps .02 amps  
Apple Mac Pro 1.28 amps .05 amps  

System Power States

  • S0 - System is on, power conservation done on a per-device basis
    • This is also known as idle or normal operation
  • S1 - CPU stops executing instructions, running in low power mode
    • It takes less than 2 seconds to go from sleeping (S1) to normal operation (S0).
  • S3 - CPU, cache, and chipset content lost, fans powered off, RAM refreshed less frequently, in "save to RAM" mode
    • This is also known as standby or sleep.
    • It takes 2 to 10 seconds to go from sleeping (S3) to normal operation (S0).
  • S4 - RAM not active, memory saved to non-volatile storage, in "save to disk" mode
    • This is also known as hibernation.
    • It takes up to 2 minutes to go from hibernation (S4) to normal operation (S0).

Further Information

Questions from potential partners about this program can be sent to us via this form.

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Last Updated November 14, 2014