Wednesday, September 16, 2009
Windows Power Management States
I've been testing Screentime screensavers on Windows 7 and realized that I needed to brush up on Windows Power Management - a very confusing subject.
I found a post by Sean Lyndersay that cleared things - Thanks Sean. I've paraphrased his take on Power Management states below.
Standby
When the PC enters this state it shuts down most components but leaves it's RAM powered.
Pros: Goes into standby fast. Comes out fast.
Cons: Uses a small amount of power. If the battery dies (or is removed), all data in memory will be lost.
Hibernate
When the PC enters this state it saves the contents of RAM to disk (in a file called hiberfil.sys) and then turns itself off completely.
Pros: Slow to go into Hibernate. Slow to come out.
Cons: Uses no power. Computer can lose power and still recover.
Sleep - New Vista Feature
When the PC enters this state it first goes into Standby. If the battery gets into a critical state, or a certain time passes (configurable in the Power Options CPL), the laptop will wake briefly from Standby then Hibernate.
This is the default behavior on a laptop. The idea is that under most circumstances, your laptop will go into power-saving mode fast, and come back out fast (you can be back to your desktop in 2 seconds or less -- about as long as it takes to open the lid of the laptop). It's also safe, because it'll save your data if the battery goes critical.
Hybrid Sleep - New Vista Feature
Hybrid Sleep is designed for desktops, not laptops. In Hybrid Sleep mode, when you click Sleep, the computer does two things:
1) Saves all of your data to disk as if it was going into Hibernation
2) Goes into standby. It stays in Standby permanently (unless you change the setting in the Power Options CPL to make it Hibernate fully at some point).
The idea is that this is better than normal sleep because if the desktop loses power while in sleep mode, it will still be able to recover because all of the data was saved.
B.
Standby
When the PC enters this state it shuts down most components but leaves it's RAM powered.
Pros: Goes into standby fast. Comes out fast.
Cons: Uses a small amount of power. If the battery dies (or is removed), all data in memory will be lost.
Hibernate
When the PC enters this state it saves the contents of RAM to disk (in a file called hiberfil.sys) and then turns itself off completely.
Pros: Slow to go into Hibernate. Slow to come out.
Cons: Uses no power. Computer can lose power and still recover.
Sleep - New Vista Feature
When the PC enters this state it first goes into Standby. If the battery gets into a critical state, or a certain time passes (configurable in the Power Options CPL), the laptop will wake briefly from Standby then Hibernate.
This is the default behavior on a laptop. The idea is that under most circumstances, your laptop will go into power-saving mode fast, and come back out fast (you can be back to your desktop in 2 seconds or less -- about as long as it takes to open the lid of the laptop). It's also safe, because it'll save your data if the battery goes critical.
Hybrid Sleep - New Vista Feature
Hybrid Sleep is designed for desktops, not laptops. In Hybrid Sleep mode, when you click Sleep, the computer does two things:
1) Saves all of your data to disk as if it was going into Hibernation
2) Goes into standby. It stays in Standby permanently (unless you change the setting in the Power Options CPL to make it Hibernate fully at some point).
The idea is that this is better than normal sleep because if the desktop loses power while in sleep mode, it will still be able to recover because all of the data was saved.
B.
Labels: Power Management, Screensaver, Windows 7
// posted by Brian @ 2:32 PM 
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