Hardware Reference
In-Depth Information
Atypicaldesktop-stylePCconsumesanywherefrom75Wto300Wwhenidlingandfrom
150W to 600W under a load, depending on the configuration, age, and design of the sys-
tem. This does not include monitors, which for LCDs range from 25W to 50W while act-
ive, whereas CRTs range from 75W to 150W or more. One PC and LCD display combin-
ation I tested consumed an average of 250W (0.25 kilowatts) of electricity during normal
operation. The same system drew 200W when in ACPI S1 Sleep mode, only 8W while in
ACPI S3 Sleep mode, and 7W of power while either turned off or hibernating (ACPI S4
mode).
Using those figures, here are some calculations for annual power costs:
Electricity Cost: $0.10 Dollars per KWh
PC/Display Power: 0.250 KW avg. while running
PC/Display Power: 0.200 KW avg. while in ACPI S1 Sleep
PC/Display Power: 0.008 KW avg. while in ACPI S3 Sleep
PC/Display Power: 0.007 KW avg. while in ACPI S4 Sleep
PC/Display Power: 0.007 KW avg. while OFF
Work Hours: 2080 Per year
Non-Work Hours: 6656 Per year
Total Hours: 8736 Per year
——————————————————————————————————
Annual Operating Cost: $218.40 Left ON continuously
Annual Operating Cost: $185.12 In S1 Sleep during non-work hours
Annual Operating Cost: $57.32 In S3 Sleep during non-work hours
Annual Operating Cost: $56.66 In S4 Sleep during non-work hours
Annual Operating Cost: $56.66 Turned OFF during non-work hours
——————————————————————————————————
Annual Savings: $0.00 Left ON continuously
Annual Savings: $33.28 In S1 Sleep during non-work hours
Annual Savings: $161.08 In S3 Sleep during non-work hours
Annual Savings: $161.74 In S4 Sleep during non-work hours
Annual Savings: $161.74 Turned OFF during non-work hours
Thismeans itwouldcostmorethan$218annually torunthesystem ifitwereleft oncon-
tinuously. However, if it were turned off during nonwork hours, the annual operating cost
would be reduced to $56, for an annual savings of more than $161! As you can see, turn-
ing systems off when they are not in use can amount to a huge savings over time.
Butevenmoreinterestingisthatyoudon'thavetoturnasystemallthewayofftoachieve
thistypeofsavings.Whenproperlyconfigured, mostPCswill enter ACPIS3Sleep mode
either manually or after a preset period of inactivity, dropping to a power consumption
level of 8W or less. In other words, if you configure the PC to enter S3 Sleep mode when
it's not active, you can achieve nearly the same savings as if you were to turn it off com-
pletely. In the preceding example, it would only cost an additional $0.66 to keep the sys-
