Save energy by enabling suspend & hibernation
March 09, 2008 by Jeremy Brock
With energy prices moving higher it is important to conserve energy both to help the environment and save money. By following these steps you can save electricity and have fast access to your computer. Most computers support suspend/hibernation however it is often not enabled or miss configured.
Background:
Computer systems normally consume around 100 to 200 watts of energy. The cost of leaving a computer on 24/7 is around $456/yr (@ $0.26kw/hr). Simply enabling suspend or hibernation mode can dramatically cut your energy usage while giving you almost immediate availability. Modern computers have three power saving modes each using less power.
- S1 Standby – The least efficient mode as only the processor and monitor enter power save mode.
- S3 Suspend (Suspend to RAM) – All devices turn off except memory which holds system state information. This is the preferred mode as it offers both fast startup and low power usage (~5watts) however some hardware may not support S3.
- S4 Hibernation (Suspend to Hard Drive) – The system state is saved to hard drive and the computer shuts off. Almost no power is consumed however startup is longer (~10seconds).
Choosing a Power Save Mode:
For desktops I prefer S3 Suspend and for laptops S4 Hibernation because the battery isn't used. S4 Hibernation maybe your only option if a device or driver is preventing your computer from entering S3 Suspend.
Enabling S3 and S4:
Computers often ship with S1 enabled. You can see which mode is enabled by going to Start->Shutdown->Standby. If your computers hard drive and fans are spinning then you’re in S1, if the computer appears to be shutdown your in S3.
To enable S3 go into the BIOS Setup then Power Management and change your suspend mode from S1 to S3.
To enable S4 open Power Options in the Control Panel and click on the Hibernation tab then click on Enable hibernation. Now when you go to shutdown you’ll see Hibernate, if not hold down the shift key.
Automatically enter S3 and S4:
Your computer can automatically enter suspend or hibernation mode if the computer has been idle for a period of time. Simply change the System standby (S3) or System hibernates (S4) values in the Power Options control panel
I find that most users are totally oblivious to the energy expenditure of their computer and other IT equipment. The common questioned asked is something like 'Should I turn off my computer?' or, 'Should I leave it on all the time?'
I recommend the following:
Going away from the computer for a short while (1-3 hours) use standby
Going away from the computer for a long while (4+ hours) use hibernation
Going away from the computer for a long time (1+ day) perform a full shut down
These are not etched in stone, they are rough guidelines.
I also disagree with the poster who mentioned that using hibernation causes excessive wear and wastes power. Either there's a misunderstanding or he/she is incorrect.
In simple terms, hibernation is saving the RAM to the disk, performing a shut down (system is completely off), and then at reboot, the hibernation file is loaded back into RAM.
Good Article.
Hi,
I like the way you laid out the importance of energy efficiency. However I have found that on some systems Hibernation causes a lot of problems with the system. I have had better success just shutting down the computer system over night, because I find that when people use hibernation is so that they never shut down there system which causes excessive wear on the system as well as burning through a lot of extra energy.
Great article and interesting website.