Dell OptiPlex N, User Manual

Page: 21 / 38

Maintaining the System 2-3
corona effects. This condition can also cause sealed com-
ponents with internal pressure, such as electrolytic
capacitors, to fail or perform at reduced efficiency.
Each Dell system is rated to operate at altitudes
from –16 to 3048 m (–50 to 10,000 ft) and can be stored
at altitudes of –16 to 10,600 m (–50 to 35,000 ft).
NOTE: At 35
°
C (95
°
F), the maximum operating altitude
is 914.4 m (3,000 ft).
Dust and Particles
A clean operating environment can greatly reduce the
negative effects of dust and other particles, which act as
insulators and interfere with the operation of a system’s
mechanical components. In addition to regular cleaning,
you should follow these guidelines to deter contamina-
tion of the computer equipment:
•
Do not permit smoking anywhere near the system.
•
Do not permit food or drink near the system.
•
Use dust covers when the system is not in use.
•
Close windows and outside doors to keep out air-
borne particles.
Corrosion
Prolonged exposure to high temperature or humidity can
corrode the gold-plated edge connectors and pin connec-
tors on various devices in the computer. This corrosion
on computer connectors is a gradual process that can
eventually lead to intermittent failures of electrical
circuits.
Protecting the system from corrosive elements is espe-
cially important in moist and salty environments, which
tend to promote corrosion. Also, as a further deterrent to
corrosion, the system should not be used in extreme
temperatures.
ESD
Electrostatic discharge (ESD) is a discharge of static
electrical charge. ESD occurs when a person whose body
contains a static electrical charge touches a part of the
computer or connector pins when connecting cables. This
static discharge can cause components, especially chips,
to fail. ESD is a problem particularly in dry environments
where the relative humidity is below 50 percent.
EMI and RFI
Electromagnetic interference (EMI) and radio frequency
interference (RFI) can travel from the computer to other
devices through the AC power cable and power source or
through the air like transmitted radio waves. They can
adversely affect devices such as radio and television
receivers operating near the computer, as well as interfere
with cordless and low-power telephones. Conversely,
RFI from high-power telephones can cause spurious
characters to appear on your monitor screen.
Various regulatory agencies, such as the Federal Commu-
nications Commission (FCC), publish regulations to limit
the amount of EMI and RFI emitted by computing equip-
ment. Each Dell system is tested for compliance with
these regulations. See Appendix A, “Regulatory
Notices,” in this guide for information on which regula-
tory agencies have tested and approved your system.
To reduce the possibility of EMI and RFI as well as to
prevent RFI from a computer affecting television recep-
tion, follow these guidelines:
•
Operate the system only with the computer cover
installed.
•
Ensure that all expansion slots are covered by a card-
mounting bracket or a metal filler bracket.
•
Ensure that the screws on all peripheral cable con-
nectors are securely fastened to their corresponding
connectors on the back of the computer.
•
Always use shielded cables with metal connector
shells for attaching peripherals to the computer.
To prevent the possibility of RFI from a computer affect-
ing television reception, follow these guidelines:
•
Keep any television at least 6 ft away from the com-
puter system.
•
Use cable television when possible.
•
Use a directional outdoor television antenna.
•
Attach line filters to the television.
•
Use 75-ohm coaxial cable for the television rather
than twin-lead antenna wire.
•
If interference occurs, rotate the computer or the
television 90 degrees.