Dell OptiPlex 390 Mini-Tower Owner's Manual

To avoid damaging your computer, perform the following steps before you beginworking inside the computer.1. Ensure that your work surface is flat and clean to prevent the computercover from being scratched.2. Turn off your computer (see Turning Off Your Computer).CAUTION: To disconnect a network cable, first unplug the cable from yourcomputer and then unplug the cable from the network device.3. Disconnect all network cables from the computer.4. Disconnect your computer and all attached devices from their electricaloutlets.5. Press and hold the power button while the computer is unplugged toground the system board.6. Remove the cover.CAUTION: Before touching anything inside your computer, ground yourself bytouching an unpainted metal surface, such as the metal at the back of thecomputer. While you work, periodically touch an unpainted metal surface todissipate static electricity, which could harm internal components.Recommended ToolsThe procedures in this document may require the following tools:• Small flat-blade screwdriver• Phillips screwdriver• Small plastic scribe• Flash BIOS update program mediaTurning Off Your ComputerCAUTION: To avoid losing data, save and close all open files and exit all openprograms before you turn off your computer.1. Shut down the operating system:• In Windows 7:Click Start , then click Shut Down.• In Windows Vista:8