Learn more about notebook power management

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Learn more about notebook power management [Copy link]

1. The concept of ACPI

　　ACPI: Advanced Configuration and Power Interface

　　ACPI has the following modes:

　　S0 Normal.
　　S1 CPU stops working.
　　S2 CPU shuts down.
　　S3 All components except memory stop working.
　　S4 Memory information is written to the hard disk, and all components stop working.
　　S5 Shut down. The power management

mode 　　using ACPI requires that both the software and hardware fully support ACPI functions.

　　If you encounter problems during use, you can try upgrading to the latest version of the Acpi.sys file.

　　In addition, hardware support for ACPI is required. When the chassis power supply provides 5 volts to the motherboard, the current must be stabilized at more than 720 mA to wake the computer from the "sleep" state in a short time.

Power management　　can be achieved by selecting a power scheme , which is a group of settings for the computer to manage power usage. Windows 2000 provides the following three preset power management schemes (Always On, Portable/Laptop, Home/Office Desktop), and users can also set the waiting time for the computer to enter standby mode or turn off the hard disk and monitor.

　　2. Comparison between ACPI and APM

　　APM 1.0 & 1.1: Power management is performed by BIOS ;

　　APM 1.2: The operating system defines the power management time, which is executed by the BIOS;

　　ACPI: BIOS collects hardware information and defines power management schemes, which are executed by the operating system.

　　APM is a software solution and is therefore operating system-dependent, whereas ACPI is an industry standard that includes both software and hardware specifications.

　　1) How to tell if the system is in S1 or S3 mode?

　　Answer: In ACPI's S1 sleep mode, only the CPU stops working, and other devices are still powered on. In ACPI's S3 mode (BIOS-> Power Management- >Suspend to RAM is set to Enable), all devices except the memory are powered off. Therefore, the easiest way to determine whether the system is in S1 mode or S3 mode is to observe the system carefully: in S3 state, all devices stop working, and the optical drive door cannot be opened even if the eject button on the optical drive is pressed. In S1 state, the optical drive door can be opened. In addition, in S3 mode, the system is completely silent and all fans are stopped. At this time, the system cannot be awakened from the keyboard. The only way to manually wake up is to press the power button on the front panel.

　　2) To realize the STR function, why can't the power be cut off after shutting down?

　　A: The STR function saves the system operation information in the memory when the computer is shut down. The next time the computer is turned on, the information in the memory is directly read and restored to the state before the shutdown. Its advantages are that the startup speed is very fast and the working state can be retained. Its disadvantage is that even after the computer is shut down, the computer power cannot be disconnected because the data in the memory will be lost once the power is cut off.

　　3) When shutting down Win2000, it displays "It is safe to shut down now" instead of automatically shutting down the ATX power supply. What should I do?

　　Answer: You can try the following method: Select "Settings/Control Panel/Power Options/Advanced Power Management ". If the machine supports advanced power management , select "Enable advanced power management support" and then set PowerdownAfterShutdown to 1 in HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsNTCurrentVersionWinlogon. If the machine does not support advanced power management , unfortunately, you can only manually cut off the power when the system is shut down and the message "Is it safe to shut down now?" is displayed.

　　4) I accidentally lost the "Put the computer to sleep" option in the "Shut Down Windows" dialog box. How can I restore it?

　　Answer: Generally speaking, this type of problem can be solved by reinstalling the motherboard driver and restarting. You can also delete the "Advanced Power Management Support" in "Control Panel/System/Device Manager", then restart the machine and reinstall it according to the prompts of the Windows 2000 system.