PC power management refers to software-based mechanisms for controlling the power use of personal computer hardware. This is typically achieved through software that puts the hardware into the lowest power demand state available, making it an aspect of green computing.
A typical office PC uses about 90 watts when active (approximately 50 watts for the base unit, and 40 watts for a typical LCD screen); and three to four watts when ‘asleep’. Up to 10% of a modern office’s electricity demand can be due to PCs and monitors. [1]
While most PCs allow low power settings, there are frequently situations, especially in a networked environment, where processes running on the computer will prevent the low power settings from taking effect. This can have a dramatic effect on energy use that is invisible to the user. Operational testing has shown that on any given day an average of over 50% of an organization's computers will fail to go to sleep, and over long periods of time this affects over 90% of machines. [1] This leads to most computers having the option of customizing power management systems and has created a market for third-party power management software to further control a computer’s power use.
The Windows power management system is based upon an idle timer. If the computer is idle for longer than the pre-set time, then the PC may be configured to sleep or 'hibernate'. Windows uses a combination of user activity and CPU activity to determine when the computer is idle.
Applications can temporarily inhibit this timer by using the ' SetThreadExecutionState ' API. [2] There are legitimate reasons why this may be necessary such as burning a DVD or playing a video. However, in many cases applications can unnecessarily prevent power management from lowering power demand. This is commonly known as Windows 'Insomnia' and can be a barrier to successfully implementing power management.
Common causes include:
Operating systems have built-in settings to control power use. Microsoft Windows supports predefined power plans and custom sleep and hibernation settings through a Control Panel Power Options applet. [3] Apple's macOS includes idle and sleep configuration settings through the Energy Saver System Preferences applet. [4] Likewise, Linux distributions include a variety of power management settings and tools. [5]
There is a significant market in third-party PC power management software offering features beyond those present in the Windows operating system. [6] [7] [8] Notable vendors Data Synergy's 'PowerMAN', [9] Faronics' 'Power Save', [10] [11] and Verdiem's 'SURVEYOR'.
Some studies have suggested that power management tools can save on average 200 kg of CO2 emissions per PC per year and generate $36 per PC per year in energy savings. [12] [13]
The following tables compare technical information for a commercial PC Power Management software suites. Please see the individual products' articles for further information. The table only includes systems that are widely used and currently available. [14] [15]
Software | Data Synergy PowerMAN [16] | Energy Star EZ GPO [17] | Faronics Power Save [18] | Verdiem Surveyor [19] |
---|---|---|---|---|
License | Proprietary | Free | Proprietary | Proprietary |
64-bit Support | Yes | No | Yes | Yes |
Active Directory Integration | Yes | No | Yes | Yes |
Group Policy Configuration Support | Yes | Yes | No | No |
Per-user Policy | Yes | No | Yes | Yes |
Per-machine Policy | Yes | Yes | Yes | Yes |
Anti-insomnia | Yes | No | Yes | Yes |
Sleep on idle | Yes | Yes | Yes | Yes |
Hibernate on idle | Yes | Yes | Yes | Yes |
Power-off on idle | Yes | No | Yes | Yes |
Logout on idle | Yes | No | Yes | No |
Standby display on idle | Yes | Yes | Yes | No |
Scheduled Sleep/Hibernate | Yes | No | Yes | Yes |
Scheduled power-off | Yes | No | Yes | Yes |
Scheduled Reboot | Yes | No | Yes | Yes |
Scheduled wake-up (without WoL) | Yes | No | Yes | Yes |
Remote wake-up (with WoL) | Yes | No | Yes | Yes |
Wake-on-LAN is an Ethernet or Token Ring computer networking standard that allows a computer to be turned on or awakened from sleep mode by a network message.
A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating systems. The term workstation has been used loosely to refer to everything from a mainframe computer terminal to a PC connected to a network, but the most common form refers to the class of hardware offered by several current and defunct companies such as Sun Microsystems, Silicon Graphics, Apollo Computer, DEC, HP, NeXT, and IBM which powered the 3D computer graphics revolution of the late 1990s.
Power management is a feature of some electrical appliances, especially copiers, computers, computer CPUs, computer GPUs and computer peripherals such as monitors and printers, that turns off the power or switches the system to a low-power state when inactive. In computing this is known as PC power management and is built around a standard called ACPI which superseded APM. All recent computers have ACPI support.
Uptime is a measure of system reliability, expressed as the percentage of time a machine, typically a computer, has been working and available. Uptime is the opposite of downtime.
Green computing, green IT, or ICT sustainability, is the study and practice of environmentally sustainable computing or IT.
Sleep mode is a low power mode for electronic devices such as computers, televisions, and remote controlled devices. These modes save significantly on electrical consumption compared to leaving a device fully on and, upon resume, allow the user to avoid having to reissue instructions or to wait for a machine to boot. Many devices signify this power mode with a pulsed or red colored LED power light.
The High Precision Event Timer (HPET) is a hardware timer available in modern x86-compatible personal computers. Compared to older types of timers available in the x86 architecture, HPET allows more efficient processing of highly timing-sensitive applications, such as multimedia playback and OS task switching. It was developed jointly by Intel and Microsoft and has been incorporated in PC chipsets since 2005. Formerly referred to by Intel as a Multimedia Timer, the term HPET was selected to avoid confusion with the software multimedia timers introduced in the MultiMedia Extensions to Windows 3.0.
Hibernation in computing is powering down a computer while retaining its state. When hibernation begins, the computer saves the contents of its random access memory (RAM) to a hard disk or other non-volatile storage. When the computer is turned on the RAM is restored and the computer is exactly as it was before entering hibernation. Hibernation was first implemented in 1992 and patented by Compaq Computer Corporation in Houston, Texas. Microsoft's Windows 10 employs a type of hibernation by default when shutting down.
Compared with previous versions of Microsoft Windows, features new to Windows Vista are very numerous, covering most aspects of the operating system, including additional management features, new aspects of security and safety, new I/O technologies, new networking features, and new technical features. Windows Vista also removed some others.
Faronics Corporation is a privately held software company with offices in Vancouver, British Columbia, Canada, Pleasanton, California, United States, Singapore and Bracknell, UK. Faronics develops computer software for multi-user IT environments.
In the x86 computer architecture, HLT
(halt) is an assembly language instruction which halts the central processing unit (CPU) until the next external interrupt is fired. Interrupts are signals sent by hardware devices to the CPU alerting it that an event occurred to which it should react. For example, hardware timers send interrupts to the CPU at regular intervals.
Intel Active Management Technology (AMT) is hardware and firmware for remote out-of-band management of select business computers, running on the Intel Management Engine, a microprocessor subsystem not exposed to the user, intended for monitoring, maintenance, updating, and repairing systems. Out-of-band (OOB) or hardware-based management is different from software-based management and software management agents.
Dynamic frequency scaling is a power management technique in computer architecture whereby the frequency of a microprocessor can be automatically adjusted "on the fly" depending on the actual needs, to conserve power and reduce the amount of heat generated by the chip. Dynamic frequency scaling helps preserve battery on mobile devices and decrease cooling cost and noise on quiet computing settings, or can be useful as a security measure for overheated systems.
To shut down or power off a computer is to remove power from a computer's main components in a controlled way. After a computer is shut down, main components such as CPUs, RAM modules and hard disk drives are powered down, although some internal components, such as an internal clock, may retain power.
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IT energy management or Green IT is the analysis and management of energy demand within the Information Technology department in any organization. IT energy demand accounts for approximately 2% of global CO2 emissions, approximately the same level as aviation, and represents over 10% of all the global energy consumption. IT can account for 25% of a modern office building's energy cost.
powercfg is a command-line utility that is used from an elevated Windows Command Prompt to control all configurable power system settings, including hardware-specific configurations that are not configurable through the Control Panel, on a per-user basis. It was first introduced by Microsoft in Windows XP SP2 in 2004.
Verdiem was a software corporation based in Seattle, Washington, USA. The company was backed by venture capital. The company was acquired by Aptean on January 12, 2015.
PowerMAN is a computer software program for central system monitoring and PC power management, of computers running Microsoft Windows operating systems. The software extends the basic features present in most operating systems to permit implementing and enforcing organization-wide power management policies.
In computing, rebooting is the process by which a running computer system is restarted, either intentionally or unintentionally. Reboots can be either a cold reboot in which the power to the system is physically turned off and back on again ; or a warm reboot in which the system restarts while still powered up. The term restart is used to refer to a reboot when the operating system closes all programs and finalizes all pending input and output operations before initiating a soft reboot.