Dell OptiPlex N User's Guide (.pdf) - Page 17

components 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 (3000 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. Also, in addition to regular cleaning, you should follow these guidelines to deter contamination 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 connectors 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 especially 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 a static electrical charge that occurs when a person whose body contains such a 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 Communications Commission (FCC), publish regulations to limit the amount of EMI and RFI emitted by computing equipment. Each Dell system is tested for compliance with these regulations. See Appendix A, "Regulatory Notices," in this guide for information on which regulatory 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 reception, 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 further prevent the possibility of RFI from a computer affecting 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. Maintaining the System 2-3