Home > Articles > CompTIA > A+

This chapter is from the book

ACPI (Advanced Configuration and Power Interface)

Today’s computer user needs to leave a computer on for extended periods of time in order to receive faxes, run computer maintenance tasks, automatically answer phone calls, and download software upgrades and patches. Network managers want control of computers so they can push out software upgrades, perform backups, download software upgrades and patches, and perform tests. Laptop users have always been plagued by power management problems, such as short battery life, inconsistent handling of screen blanking, and screen blanking in the middle of presentations. Such problems occurred because originally the BIOS controlled power. Power management has changed.

ACPI (Advanced Configuration and Power Interface) gives the BIOS and operating system control over various devices’ power and modes of operation, as shown in Figure 4.28.

Figure 4.28

Figure 4.28. ACPI actions

With ACPI, the user can control how the power switch operates and when power to specific devices, such as the hard drive and monitor, is lowered. For example, the Instant On/Off BIOS setting can control how long the power switch is held in before the power supply turns on or off. Case temperatures, CPU temperatures, and CPU fans can be monitored. The power supply can be adjusted for power requirements. The CPU clock can be throttled or slowed down to keep the temperature lower and prolong the life of the CPU and reduce power requirements especially in portable devices when activity is low or nonexistent. ACPI has various operating states, as shown in Table 4.3.

Table 4.3. ACPI operating states

Global system state

Sleep state

Description

G0 Working

(S0)

The computer is fully functional. Software, such as the autosave function used with Microsoft products, can be optimized for performance or lower battery usage.

G1 Sleeping

Requires less power than the G0 state and has multiple sleeping states: S1, S2, S3, and S4.

(S1)

CPU is still powered, and unused devices are powered down. RAM is still being refreshed. Hard disks are not running.

(S2)

CPU is not powered. RAM is still being refreshed. System is restored instantly upon user intervention.

(S3)

Power supply output is reduced. RAM is still being refreshed. Some info in RAM is restored to CPU and cache.

(S4)

Lowest-power sleep mode and takes the longest to come up. Info in RAM is saved to hard disk. Some manufacturers call this the hibernate state.

G2

(S5)

Also called soft off. Power consumption is almost zero. Requires the operating system to reboot. No information is saved anywhere.

G3

Also called off, or mechanical off. This is the only state where the computer can be disassembled. You must power on the computer to use it again.

Two common BIOS and adapter features that take advantage of ACPI are Wake on LAN and Wake on Ring. The Wake on LAN feature allows a network administrator to control the power to a workstation remotely and directs the computer to come out of sleep mode. Software applications can also use the Wake on LAN feature to perform updates, upgrades, and maintenance tasks. The feature can also be used to bring up computers immediately before the business day starts. Wake on LAN can be used with Web or network cameras to start recording when motion is detected or to bring up a network printer so that it can be used when needed. Wake on Ringallows a computer to come out of sleep mode when the telephone line has an incoming call. This lets the computer receive phone calls, faxes, and emails when the user is not present. Common BIOS settings related to ACPI are listed in Table 4.4.

Table 4.4. Common BIOS power settings

Setting

Description

Delay Prior to Thermal

Defines the number of minutes the system waits to shut down the system once an overheating situation occurs.

CPU Warning Temperatures

Specifies the CPU temperature at which a warning message is displayed on the screen.

ACPI Function

Enables or disables ACPI. This is the preferred method for disabling ACPI in the event of a problem.

Soft-off

Specifies the length of time a user must press the power button to turn off the computer.

Deep S4/S5

Uses less power and only wakes from S4/S5 states with the power button or a RTC (real time clock) alarm, such as waking the computer to complete a task.

Power on by Ring, Resume by Ring, or Wakeup

Allows the computer to wake when an adapter or an external device supports Wake on Ring.

Resume by Alarm

Allows a date and time to be set when the system is awakened from Suspend mode. Commonly used to update the system during nonpeak periods.

Wake Up on LAN

Allows the computer to wake when a Wake on LAN signal is received across the network.

CPU THRM Throttling

Allows a reduction in CPU speed when the system reaches a specific temperature.

Power on Function

Specifies which key (or key combination) will activate the system’s power.

Hot Key Power On

Defines what keystrokes will reactivate system power.

Doze Mode

When the system is in a reduced activity state, the CPU clock is throttled (slowed down). All other devices operate at full speed.

After Power Failure

Sets power mode after a power loss.

Windows 7 has three power plans available, and you can customize these power plans. You might want to customize a power plan when there is a problem with poor video quality when playing a movie. Use the Change plan settings link followed by the Change advanced power settings link to expand a section such as the Multimedia settings option. Table 4.5 shows the three main power plans you can just click and select.

Table 4.5. Windows 7 power plans

Power plan

Description

Balanced

The most common plan because it provides full power when you need it and saves power when the computer is not being used.

Power saver

Saves power by running the CPU more slowly and reducing screen brightness.

High performance

Select the Show additional plans link to see this option. This provides the maximum performance possible.

Sometimes, when a computer comes out of Sleep mode, not all devices respond, and the computer’s power or reset button has to be pressed to reboot the computer. The following situations can cause this to happen:

  • A screen saver conflicts with ACPI
  • All adapters/devices are not ACPI compliant
  • An adapter/device has an outdated driver
  • The system BIOS or an installed adapter BIOS needs to be updated

To see if the screen saver causes a problem, use the Display Control Panel and set the screen saver option to None. Identifying a problem adapter, device, or driver will take Internet research. Check each adapter, device, and driver one by one. Use the Power Options Control Panel to change the power scheme. Also check all devices for a Power Management tab on the Properties dialog box. Changes can be made there.

Links on the left of the Power Options Control Panel provide access to advanced settings such as requiring a password to come out of sleep mode. The power options for a Windows 7 laptop are shown in Figure 4.29.

Figure 4.29

Figure 4.29. Windows 7 power settings

Other laptop Power Options Control Panel settings include the following links: Require a password on wakeup, Choose what the power button does (as shown in Figure 4.29), Choose what closing the lid does, Create a power plan, Choose when to turn off the display, and Change when the computer sleeps. Laptop power settings affect battery life. Users and technicians should adjust these settings to best fit how the laptop or mobile device is used.

In Windows Vista and 7, use the Power Options Control Panel to edit the power settings. Select the Change advanced power settings link to configure passwords, standby power behavior, and other power-related settings. If the computer does not go into the Sleep mode, check the following:

  • Determine if ACPI is enabled in BIOS.
  • Try disabling the antivirus program to see if it is causing the problem.
  • Set the screen saver to None to see if it is causing the problem.
  • Determine if all device drivers are ACPI compliant.
  • Determine if power management is enabled through the operating system (use the Power Options Control Panel).
  • Disconnect USB devices to see if they are causing problems.

Pearson IT Certification Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Pearson IT Certification and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Pearson IT Certification products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by Adobe Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.pearsonitcertification.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020