Hardware Reference
In-Depth Information
Temperature variations can lead to serious problems. If extreme variations occur over
a short period, signal traces on circuit boards can crack and separate, solder joints can
break, and contacts in the system can undergo accelerated corrosion. Solid-state compon-
ents such as chips can be damaged also, and a host of other problems can develop.
To ensure that your system operates in the correct ambient temperature, you must first de-
termine your system's specified functional range. Most manufacturers provide data about
the correct operating temperature range for their systems. Two temperature specifications
might be available, one indicating allowable temperatures during operation and anoth-
er indicating allowable temperatures under nonoperating conditions. Many manufacturers
list the following temperature ranges as acceptable for most systems.
System on: 60°-90° Fahrenheit
System off: 50°-110° Fahrenheit
Most office environments provide a stable temperature in which to operate a computer
system, but some do not. Be sure to give some consideration to the placement of your
equipment.
Power Cycling (On/Off)
Asyouhavejustlearned,thetemperaturevariationsasystemencountersgreatlystressthe
system's physical components. The largest temperature variations a system encounters,
however, are those that occur during the warm-up period right after you turn on the com-
puter. Powering on a cold system subjects it to the greatest possible internal temperature
variations. If you want a system to have the longest and most trouble-free life possible,
you should limit the temperature variations in its environment. You can limit the extreme
temperaturecyclingintwosimpleways:Leavethesystemoffallthetimeorleaveitonall
the time. Of these two possibilities, of course, you probably will want to choose the latter
option. Leaving the power on is the best way I know to promote system reliability. If your
only concern is system longevity, the simple recommendation is to keep the system unit
powered on (or off!) continuously. In the real world, however, there are more variables
to consider, such as the cost of electricity, the potential fire hazard of unattended running
equipment, and other concerns as well.
If you think about the way light bulbs typically fail, you can begin to understand how
thermal cycling can be dangerous. Light bulbs burn out most often when you first turn
them on because the filament must endure incredible thermal stress as it changes temper-
ature, in less than one second, from ambient to several thousands of degrees. A bulb that
remains on continuously lasts longer than one that is turned on and off repeatedly. If you
use CFLs, estimated power savings can be achieved only if the lights are left on for long
