Dell OptiPlex N User's Guide (.pdf) - Page 22

Magnetism Because they store data magnetically, hard-disk drives are extremely susceptible to the effects of magnetism. Speakers Audio speakers can be a source of magnetic energy if they are not properly shielded. Speakers used in music systems are typically enclosed in wooden cabinets, which provide no magnetic shielding. Multimedia speakers for computer systems are magnetically shielded inside a metallic case and are thus the only type of speakers recommended for use with multimedia computer systems. Shock and Vibration Excessive shock can damage the function, external appearance, and physical structure of a system. Excessive vibration can cause the same problems as excessive shock does and can cause components to become loose in their sockets or connectors. Systems can be subjected to significant vibration when being transported by vehicle or when operated in an environment with machinery that causes vibration. Each Dell system, when operating, is designed to withstand a left side (for vertical orientation using the optional stand) and bottom half-sine pulse with a change in velocity of 50.8 centimeters per second (cm/sec) (20 inches/sec). In storage, the system can withstand a 26478-cm/sec2 (27-gravities) faired square wave with a velocity change of 508 cm/sec (200 inches/sec). Power Source Interruptions Computer systems are sensitive to variations in voltage supplied by the AC power source. Overvoltage, undervoltage, and transients (or spikes) can erase data from memory or even cause components to fail. To protect against such problems, power cables should always be properly grounded, you should use a power protection device, and you should place the system on a circuit that does not contain any heavy electrical equipment. Your network administrator should verify your power source and network cables; however, you should ensure that your system is connected to a dedicated power circuit and that it is not sharing a circuit with any of the following: • Kitchen appliances • Copier machines • Air conditioners • Vacuum cleaners • Space heaters • Power tools • Teletype machines • Adding machines • Any other motorized equipment Another threat to a system's supply of power is surges or blackouts caused by electrical storms. Whenever possible, turn off the computer and any peripherals and unplug them from their power sources during thunderstorms. If a blackout occurseven a temporary oneturn off the system immediately and disconnect it from its power source. Leaving the system on may cause problems when the power is restored; all other appliances left on in the area can create large voltage spikes that could damage the system. Power Protection Devices Various levels of power protection are available for your system. Surge Protectors Surge protectors prevent voltage spikes, such as those caused during electrical storms, from entering a system through the AC power source. These devices are available in a variety of types and usually provide a level of protection commensurate with the cost of the device. 2-4 Dell OptiPlex N Systems User's Guide