Computer Power Consumption

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Computer Power Consumption

• Created By Paul Briskey
• February 18, 2008

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Outline

• Computer Power States
• Computer Power Consumption Factors
• Notes On Energy Star
• Power Test System Configuration
• Power Test Results
• Conservation Steps and Software Notes
• Changing Power Management Settings
• Sources

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Computer Power States
Power State Description
S0 (At Desktop) Normal working state (either idle or active). Computer is ready to go.
S3 (Sleeping) Monitor, HDD, and other peripherals are turned off but RAM is still on and holding data. Fastest to wake up.
S4 (Hibernating) All data in RAM is stored to the HDD and everything is shut down. Medium amount of time to wake up.
S5 (Power Off/Mechanical Off) Computer is off but still plugged in. Must go through full boot process.
G3 (Power disconnected) Power strip is off or computer is not plugged in. Must go through full boot process.
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Computer Power Consumption Factors

• Everything makes a difference
• Power consumption is based on voltage levels and
  current requirements. These will vary
  drastically not only with component attributes
  (i.e., processor speed), but also between brands.
• Power management options in the operating system
  as well as in the motherboard BIOS also change
  consumption.
• Performance often precludes power savings
• Increases in speed result in more power use. For
  example, an increase in memory speed causes it to
  become unstable so the memory voltage is
  increased. This directly results in more power
  use.

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Notes On Energy StarFor Computers/Motherboards

• Energy Star is a product certification that
  manufacturers can apply for.
• Each product type (desktop, server, etc.) has
  several categories, each with different
  qualifications.
• Compliance is taken very seriously since ONE
  failed test at any time prohibits certification
  for the failed product indefinitely.
• Test conditions are specified by the
  manufacturer. Therefore, an E-Star compliant
  system might only pass when specific parts are
  used and many system options are disabled.

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Power Test System Configuration
Gaming System Multimedia System Energy Star Board
Board Intel D975XBX2 NVIDIA nForce660
Processor Intel Core2 Extreme (45nm, 1.165V) Intel Pentium Extreme (65nm, 1.525V) Multi-core
RAM 2GB PC2-5300 (1.8V) 4GB PC2-6400 (2.2V) gt2GB
HDD 500GB SATA II 200GB SATA II 300GB SATA II 500GB SATA II 240GB IDE 120GB IDE gt2 HDD
Graphics Card GeForce 8800GTS-512 GeForce 7900GTX-512 gt128MB dedicated
Sound Card X-FI Xtreme Music X-FI Xtreme Music None
Other TV Tuner Card, PCI USB Card, 4- 120mm and 1- 140mm case fans, DVD ROM (IDE), DVD-RW (IDE) TV Tuner Card, 2- 120mm case fans, Wireless-G Network Card, 13in1 Card Reader TV Tuner/Video Capture Card
Note Parts list is not exhaustive. Energy Star
configuration for Class C desktop board
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Power Test Results
Power State Gaming System Gaming System Multimedia System Multimedia System E-Star Board E-Star Board
S0 (Active) 250W 250W 300W 300W - -
S0 (Idle) 163W 163W 212W 212W lt95W lt95W
S3 (Sleep) 7W 7W 6W 6W lt4W lt4W
S5 (Off) 6W 6W 5W 5W lt2W lt2W
kWh/ month Cost/month _at_ .10/kWh kWh/ month Cost/month _at_ .10/kWh kWh/ month Cost/month _at_ .10/kWh
S0 (Idle) 117.36 11.74 152.64 15.26 lt68.4 lt6.84
S3 (Sleep) 5.04 .50 4.32 .43 lt2.88 lt.29
S5 (Off) 4.32 .43 3.6 .36 lt1.44 lt.14
E-Star board power requirements are based on the
Intel Desktop Class C standard (classes A and B
have more stringent power requirements). Active
Test Running 3DMark06
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Conservation Steps Software Notes

• To Conserve Energy
• Turn your computer off at night. (Basic)
• Change power management options on your computer.
  (Intermediate)
• Disable unnecessary motherboard options.
  (Advanced)
• Disable unused hardware in the device manager or
  set it to enter low power mode when not used.
  (Advanced)

• Using Software
• You can download software to change power
  management options for you. Many systems already
  include this.
• If you can do it yourself (it is very straight
  forward) you will avoid another program running
  in the background slowing your computer down.
• This software is not capable of changing any
  motherboard options in BIOS

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Changing Power Management Settings
1. Right click on the desktop and select
Properties
2. Select the Screen Saver tab and click
Power

• 3. Select a power scheme and hit OK

? Explore this dialogue to find other options for
power saving
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Sources

• Bolioni, Thomas, et al. Energy Star System
  Implementation. April 2007. Intel Corporation.
  18 February, 2008.
• lthttp//cache-www.intel.com/cd/00/00/33/90/339085
  _339085.pdfgt