Microsoft recently released a new 14-page whitepaper entitled “
Windows 7 Power Management” to outline the power management technologies in Windows 7 that reduce power consumption. For those curious as to how exactly Windows 7 will use less power, this is your answer. For those who just want the quick scoop, here are 8 different ways how Windows 7 mainly save battery life:
1) Idle Resource Utilization
This is one of the most important power management technologies because idle time is a significant portion of the time a computer is turned on. Idle efficiency in Windows 7 is improved by reducing resource utilization and enabling hardware to go into lower power states during long periods of inactivity. This includes the processor, disk, memory, and network activity on the computer. To demonstrate just how much power can be saved, CPUs consume nearly 0 watts when idle, but up to 35 watts at full power.
2) Trigger Start Services
Services were usually started automatically right after startup and would run in the background waiting for an event to occur. In Windows 7, certain services are only started when triggered by an event such as device insertion or an IP change. This makes it unnecessary to have services starting all the time and reduces the amount of background processes.
3) Enhanced Processor Power Management
Windows 7 will include device driver support for the latest PPM technologies. PPM allows Windows 7 to choose the appropriate processor performance state depending on the load and scale performance accordingly.
4) Adaptive Display Brightness
Microsoft says that the average display is set to turn off after 10-15 minutes of inactivity. Often times however, there are shorter periods of inactivity in between. To save additional power, ADB defines will allow dimming the display. ADB can also utilize hardware sensor technology to adjust display brightness accordingly to ambient light.
5) Low-Power Audio
Windows 7 will support the latest Intel HD Audio low-power specification, which introduces a new power state known as D3Cold. This is the lowest unresponsive power state that a codec can go into. It can also further conserve power when an audio device is not in use. Windows 7 also supports selective suspend technology that extends to USB audio-class devices such as microphones and web-cams.
6) Timer Coalescing
Modern processors reduce power consumption by taking advantage of idle time between executing instructions, but many PPM technologies require a minimum amount of idle time before obtaining any net-power savings. Timer Coalescing increases the average idle period by letting the Windows kernel combine periodic software activity.
Additionally, Windows 7 will defer non-critical background activity when the user is on a battery-powered setup (netbook or notebook).
7) Bluetooth Power Improvements
Windows 7 will enable a state of “selective suspend” when it detects that a Bluetooth device has entered a low-power state.
8) Networking Power Improvements
Network adapters enter a lower-power state (known as D3) if supported by the adapter and driver whenever a network cable is removed. Low-power mode capability for wireless network controllers has been improved. Low-power mode is only entered if the access point supports it. Vista was unable to detect if the mode was supported and would cause computers to suddenly disconnect from the wireless network. Windows 7 will detect compatibility before entering the low-power mode.
9) Optimizations to key user scenarios
In addition to the improvements listed above, Microsoft also looked at specific key scenarios they could optimize including search, Internet browsing, and casual gaming. Here is an example of some of the optimizations made to a DVD Playback scenario:
- The ability for the CPU to stay in lower performance states without affecting playback performance
- Improvement of the Desktop Windows Manager (DWM) and Graphics Processing Unit (GPU) utilization through architectural changes
- Smart data caching that allow optical disk drive spin-down
These are the nine key ways Windows 7’s power management will improve, saving a lot more battery life than its predecessors on portable computing. In addition to these great improvements are power-management diagnostics to help IT pros determine problems that may be affecting power efficiency. For full technical info and additional resources, click here to check out Microsoft’s site to download the whitepaper.
Enjoy!
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