About Your System 15• Always attach an external device while your system and the device are turned off. Next, turn on anyexternal devices before turning on the system (unless the documentation for the device specifiesotherwise).See "Using the System Setup Program" on page 29 for information about enabling, disabling, andconfiguring I/O ports and connectors.NIC Indicator CodesEach NIC on the back panel has an indicator that provides information on network activity and linkstatus. See Figure 1-3. Table 1-3 lists the NIC indicator codes.Figure 1-3. NIC IndicatorsSystem MessagesSystem messages appear on the screen to notify you of a possible problem with the system. Table 1-4 liststhe system messages that can occur and the probable cause and corrective action for each message.NOTE: If you receive a system message that is not listed in Table 1-4, check the documentation for the applicationthat is running when the message appears or the operating system's documentation for an explanation of themessage and recommended action.CAUTION: Only trained service technicians are authorized to remove the system cover and access any of thecomponents inside the system. Before performing any procedure, see your Product Information Guide for completeinformation about safety precautions, working inside the computer and protecting against electrostatic discharge.1 link indicator 2 activity indicatorTable 1-3. NIC Indicator CodesIndicator Indicator CodeLink and activity indicators are off. The NIC is not connected to the network.Link indicator is green. The NIC is connected to a valid link partner on the network.Activity indicator is blinking yellow. Network data is being sent or received.1 2
