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How is IT Services addressing the need to save energy?

The ITS-supported computers range from new up to about 5 years old. Over 800 of these computers are in "cluster rooms", and many of these are accessible 24 hours per day.


ITS update the model used regularly to take advantage of the latest energy saving technology. Features include  90% efficient power supply, and is Energy Star 5.0 compliant with Active PFC.
On average, when idle, the machine consumes 15W. When shut down or hibernated but still connected to the mains, it consumes 0.8W.  If a shut-down or hibernated computer is disconnected from the mains, the only power it consumes is that of its internal rechargeable battery.


All machines managed by ITS have flat screen monitors, the latest using LED technology. These typically consume about 25 - 70W when in use, and 0.5 - 1.5W when in Standby.

Computer Energy-Saving Settings

All the cluster computers using Microsoft Windows are controlled by power-management software (PowerMan) which functions as follows:

  1. After 15 minutes of inactivity the computer's monitor goes into Standby mode with a blank screen. You need only move mouse to resume work.
  2. After further 5 minutes inactivity, the computer is logged off.
  3. After 10 minutes showing the 'login' screen the computer enters sleep/hibernation, according to its built-in capability.

A computer in sleep mode will normally return to operation in 10 seconds after the mouse is moved or a keyboard key is pressed. If a computer has been shut down or hibernated then the power button must be pressed to restart the computer.

The PowerMan system also reawakens clustered computers at set times (currently 5am) in order to perform scheduled tasks such as updates.  Once updates are completed, the computers are returned to sleep/hibernation if not in use.

The lecture theatre and seminar room PCs have slightly different settings. After 120 minutes of inactivity the computer is logged off but the monitor does not go into Standby during that period. After 15 minutes showing the 'login' screen the computer enters sleep/hibernation, according to its built-in capability.

Other PCs managed by ITS also have power saving built into their configuration. They are set so that a screen saver cuts in after 12-15 minutes (but without power saving), and 5-8 minutes later the monitor switches down into standby (providing a significant power saving).

Further Information

Click on the links below to find out more.

High Efficiency 88% efficient power supplies

Energy Star 5.0 Compliance

Advanced Configuration and Power Interface (ACPI)

Dell Optiplex 760 power consumption

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This is question number 1210, which appears in the following categories:

Created by Andy Clews on 15 February 2006 and last updated by Neale Type on 26 June 2017