Power Supplies - Upgrading and Repairing PCs - page 1146

tem in Stand By mode during nonwork hours versus turned completely off, still resulting
in an annual savings of more than $161.
With the improved power management capabilities of modern hardware, combined with
the stability and control features built into modern OSs, systems can Sleep and Resume
almost instantly,without havingtogothroughthelengthy shutdownandcoldbootstartup
procedures over and over again. I'm frankly surprised at how few people I see taking ad-
vantage of this because it offers both cost savings and convenience.
Many people perform a full shutdown procedure when turning off their computer, closing
all open applications, shutting down the OS and system completely. Then when powering
back on, they do a cold boot and reload the OS, drivers, and applications from scratch.
There is an alternative that is much better. Instead of shutting down completely, put the
system to Sleep instead. When in Sleep mode the system saves the full system context
(stateofthesystem,contentsofRAM,andsoon)inRAMbeforepoweringoffeverything
but the RAM. Unfortunately, many systems aren't configured to take advantage of Sleep
mode,especiallyolderones.NotethatSleepwascalledStandby(orStandby)inWindows
XP and earlier.
The key is in the system configuration, starting with one important setting in the BIOS
Setup. The setting is called ACPI suspend mode , and ideally you want it set so that the
system will enter what is called the S3 state. S3 is sometimes called STR for Suspend to
RAM . That has traditionally been the default setting for laptops; however, many if not
mostdesktopsunfortunatelyhaveACPIsuspendmodesettotheS1statebydefault.ACPI
S1 is sometimes called POS for Power on Suspend , a state in which the screen blanks and
CPUthrottlesdown;however,almosteverythingelseremainsfullypoweredon.Asanex-
ample,asystemandLCDdisplaythatconsumes250Wwillgenerallydroptoabout200W
while in S1 Sleep; however, the same system will drop to only 8W of power consumption
in the S3 (Suspend to RAM) state.
When the system is set to suspend in the S3 state, upon entering Sleep (either automat-
ically or manually), the current system context is saved in RAM and all the system hard-
ware (CPU, motherboard, fans, display, and so on) except RAM is powered off. In this
mode, the system looks as if it is off and consumes virtually the same amount of power
as if it were truly off. To resume, you merely press the power button just as if you were
turning the system onnormally.Youcan configure most systems toresume onakeypress
or mouse click as well. Then, instead of performing a normal cold boot and full restart,
the system almost instantly powers on and resumes from Sleep, restoring the previously
saved context. Your OS, drivers, all open applications, and so on, appear fully loaded just
as they were when you “powered off.”