Knowledgebase: Windows 7
Computer Power Management
Posted by Aaron Klein on 25 February 2011 10:53 AM

Computer Power Management

Beginning in the spring of 2011 the IT Center has begun implementing new power management schemes across campus to the various computers around campus. The purpose of this was to take advantage of the new power management capabilities within Windows 7. These new features will permit us to lower the overall energy consumption associated with the college computers by more than 50%. In the past we encouraged users to leave the computers powered on after leaving for work and over the weekend. This is because we schedule various tasks to occur over the night time hours so as to have a minimal affect on you the user. One of the new features with Windows 7 is the ability to schedule the computer to 'wake up'. This permits us to put the system in a low power state when the system is not in use while at the same time having the system power on at the correct time to perform regular nighttime functions. The table below will summarize the changes we have implemented. The IT Center has done extensive testing with these settings prior to implementing these changes campus wide. As the end user you should see very little changes with respect to these new power management settings.

Computer RoleMonitor DimmingHard drive Spin DownHibernation
Standard Office Computer20 Minutes between 8am-5pm, 10 Minutes after 5pm15 minutes of idle between 8am and 5pm, 10 minutes of idle after 5pmDisabled between the hours of 8am and 5pm, after 30 minutes of idle after 5pm.  System wakes up at 2:55am
Classroom ComputerAfter 2 hours between 7am and 9pm, 20 minutes of idle after 9pmAfter 20 min of of idle between 7am and 9pm, 20 minutes of idle after 9pm

Disabled between 6:30am and 10pm, after 45 min of idle after 10pm.  System wakes up at 6:30 am

Computer Lab System20 minutes between 6am and 12am, 10 minutes of idle after 12am10 minutes of idle between 6am and 12am, after 10 minutes of idle after 12amDisabled between 6am and 12am, after 1 hour of idle after 12am.  System wakes up at 5:55 am
Remote Access Office Computer20 Minutes between 8am-5pm, 10 Minutes after 5pm15 minutes of idle between 8am and 5pm, 10 minutes of idle after 5pmDisabled (users can not remote into office computer if it is in low power state)

Monitor Dimming - This feature will place the display in a low power state after the specified period of time. The display is not turned off it is simply not displaying an image. Moving the mouse or pressing a key on the keyboard will wake the display up within a second or two. This setting is not the same as a screen saver that you may have set within Windows 7.

Hard drive spin down - The hard drive that is within each computer has spinning platters. These platters are spinning at all times during normal computer use so the data on the hard drive will be quickly accessible. There is no need to keep these platters spinning if the user is not actively using the system. By spinning down the hard drive when the system is idle the amount of heat generation as well as power consumption can be reduced. Just like with the monitor dimming feature moving the mouse or pressing a key on the keyboard will cause the drive to spin back up. There may be a slight delay in the computer's responsiveness during this spin up but it should last no longer than 3 seconds.

Hibernation - This is the most pronounced setting that will reduce the power consumption of a system. For all of the roles above the systems are configured to not hibernate during peak periods of usage. During periods of time where usage is less likely the systems are configured to go into a low power state after a period of idle, basically the time since the last movement of the mouse or use of the keyboard. Users may still use the computers during the hours that hibernation is enabled. To wake the system up from hibernation the user must depress the power button. Once this is done the system should quickly 'wake up' and be ready to login within 10 seconds or so. In all instances if a user is logged in the user will need to enter their password when the system wakes up from hibernation. If the person whom wakes the system up is not the user that was previously logged in they can click on the "Switch User" button to enter their own username and password.

The classroom computers as well as the computer lab computers they are set to wake up in early morning hours of 6:30am and 5:55am respectively. This is to permit these systems to perform their maintenance tasks well in advance of users needing them for usage. They will then remain on throughout the day. Users will only need to wake them up from hibernation should they need to use the system between the hours of 9:45pm - 6:30pm for classroom systems and 12am and 5:55am for lab systems.

Standard office systems will wake up at 2:55am to perform the scheduled maintenance that is to occur at 3am. They will then go back into hibernation mode once this work is complete.  Additionally laptop computers will not wake up.  This is by design to prevent them from waking up when on battery and possibly running out of battery power.

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