Introduction to connected standby

The connected standby power model enables Windows PCs to provide an instant-on, always-connected experience, similar to that of smartphone devices. The underlying power-management technologies that support connected standby are dramatically different from what's required to support the traditional ACPI Sleep (S3) and Hibernate (S4) states. Connected standby is supported starting with Windows 8 and Windows 8.1.

This section provides an overview of the connected standby power model, including software, hardware, device, and firmware operation. System manufacturers who are building their first connected standby PCs are encouraged to read this content early in the platform design process to make sure that their hardware and firmware designs are compatible with connected standby.

Benefits of connected standby

Connected standby brings the smartphone power model to the PC. It provides an instant-on, instant-off experience that users have come to expect on their smartphone. And just like on the smartphone, the system remains connected, thereby enabling applications to stay fresh, up-to-date, and reachable whenever a suitable network is available.

Connected standby has multiple advantages compared to the end-user experience that traditional ACPI Sleep (S3) and Hibernate (S4) states deliver. The most prominent benefit is instant resume from sleep. Connected standby PCs resume from sleep extremely quickly—typically in less than 500 milliseconds. The performance of a resume from connected standby is almost always faster than a resume from the traditional Sleep (S3) state and significantly faster than a resume from Hibernate (S4) or Shutdown (S5).

When the user powers on the system, the connected standby PC is already connected to Wi-Fi so that apps load faster and the user doesn't have to wait for the system to first associate with a Wi-Fi access point. Connected standby PCs can provide the user with Mail notifications during connected standby and alert the user to incoming Skype calls.

Windows PCs must be designed from the beginning to support connected standby. Connected standby PCs include low-power core silicon and memory, solid-state storage, offload-capable Wi-Fi, and power-efficient mainboard design. Windows 8 and Windows 8.1 include many operating system-level changes to achieve power efficiency during connected standby, including built-in capability to reduce power by suspending and pausing applications.

This section describes the benefits, system design, and functional operation of connected standby on capable Windows PCs. Readers are also encouraged to review Validating Connected Standby for information about test and development for connected standby systems.

The remainder of this section pertains to PCs that implement the connected standby power model.

In this section

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What is connected standby?

Starting with Windows 8 and Windows 8.1, connected standby is a new low-power state that features extremely low power consumption while maintaining Internet connectivity. For a PC that implements the connected standby power model, the connected standby power state serves as the primary off mode for the PC—similar to the off mode that a smartphone enters when the user presses the power button.

Connected standby user experiences

Connected standby is more than just a low-power sleep state—it is part of many fundamental Windows 8 and Windows 8.1 user experiences. When the screen is off, the connected standby state is presented to the user as the system "sleep" state.

Platform design for connected standby

To support connected standby, a PC hardware platform must meet a specific set of requirements. These requirements govern the selection of the SoC chip, DRAM, networking device, and other key hardware components.

Functional overview of connected standby

Windows achieves the low-power and constant connectivity of connected standby by dramatically reducing the opportunities for software components to execute. Windows allows software to execute only in short, controlled bursts of activity. Windows and the SoC hardware are always listening for interesting events (such as a network packet or user input at a keyboard) and will wake up instantly when needed.

Functionality with networking devices

To support connected standby, Windows is designed to use the right network adapter at the right time for an Internet connection. All connected standby PCs have a Wi-Fi adapter, but some PCs also have a mobile broadband (MBB) adapter and/or a wired Ethernet adapter. During connected standby, Windows automatically connects to the best available network.

Other connected standby functionality

Additional activities that occur during connected standby include Automatic Maintenance. The reason to perform maintenance activities during connected standby is to avoid interrupting users when they are actively using the system. Windows performs these activities with minimal impact on connected standby battery life.

Power policy configuration

Connected standby support has significant impact across all system components: hardware, devices, drivers, apps, and Windows itself. Several power policy behaviors are changed in Windows if a PC implements connected standby instead of the traditional ACPI Sleep (S3) state.

Integrating apps with connected standby

Most apps that are built for Windows do not need any additional support to run in a connected standby system. Windows Store apps are already designed to separate background activity from the interactive pieces of the app by using background tasks.

 

Note  The Windows operating system and customer-facing Windows marketing material refers to connected standby as InstantGo. However, this section uses the connected standby terminology that should be familiar to Windows hardware partners, firmware developers, and driver developers who are the target audience of the connected standby documentation.

 

 

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