Power Management Setup

Now that we’ve seen the major advanced setup options, we will discuss the PC advanced power management setup, which is performed by means of the setup Power Management menu.

The PC has several sleep modes in order to save electrical power. This is obtained in several different ways, as for instance, reducing the processor clock frequency or turning off the hard disk. Naturally the PC only goes into sleep mode after a determined inactive time period, that is, without executing any task at all. It is right in the power management menu that you set up the appropriated inactivity time needed before the PC goes into the sleep mode.

There are three sleep modes: Doze, Standby and Suspend. The difference between them is the sleeping “deepness”. The deeper the sleep, the more energy you’ll save. The Doze mode is the most superficial and the Suspend mode is the deepest.

At setup you set the inactivity time needed before PC goes into those sleeping modes. Additionally you’ll set up the length of the inactivity period of time before the hard disk is turned off (IDE Power Control or HDD Power Down Time options) and you may even set up the option to turn off the processor fan when it goes into sleeping mode (CPU Fan Off option). As the processor clock is reduced in that mode, the fan may be turned off, as the processor will not heat as much.

You may also set up the activity type allowed to wake up the PC. Modem is a good example. It is quite common to use the modem as a fax and let the PC on throughout the day waiting for fax calls. In order to save energy, you can set up the PC to stay in sleeping mode and to wake up at the reception of a fax call, then going back into sleeping mode after an inactivity period. This facility is called Wake-up On Ring.

Most setups show an option where an interruption request (IRQ) wakes up the PC. This means that any activity in the device using that IRQ will wake up the PC. The keyboard, for instance, uses interruption 1 (IRQ1). Consequently if you set that IRQ1 wakes the PC up, that is to say that any keyboard activity will wake up the PC. The same happens with any device connected to the PC as for instance, the serial mouse, which usually uses IRQ4 (that is setting IRQ4 to wake the PC up, it jumps out of sleeping mode whenever you move the mouse). You can get a complete list of the relations between devices and IRQ in your computer by means of the Device Manager (an icon in the Control Panel System), selecting Computer and clicking in the Properties box.

When power management is enabled, Windows 98 displays a new option in the Start menu: Suspend. This options puts the PC immediately into Suspend Mode and no programmed inactivity time needs to be timed out.

Occasionally your PC may display many other options in the power management menu, but we expect that you will be able to set them up intuitively grounded on today’s discussions.


Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.