Dell PowerEdge 850 - Manual (Page 135)

System Board
The system board provides interface signal routing between the system board and the two SATA hard-drive bays, the optional CD drive, and the control panel.
In addition, the power supply is connected to the system board using two cables.
The system board and system board tray are removed and replaced as a single assembly.
Removing the System Board Assembly
1. Open the system. See " Opening the System " in "Troubleshooting Your System."
2. Remove the cooling shroud. See " Removing the Cooling Shroud " in "Installing System Components."
3. Remove the heat sink and processor. See " Replacing the Processor " in "Installing System Components."
4. Remove the memory modules. See " Removing Memory Modules " in "Installing System Components."
5. Remove the fan module. See " Removing the Fan Assembly " in "Installing System Components."
6. If applicable, disconnect the optical drive interface cable from the daughter card connector PRI_IDE1. See Figure A -3 .
7. Disconnect the two control-panel interface cables from the FRONT_PANEL connector on the system board and the USB_CONN connector on the daughter
card. See
Figure A -3 .
8. Disconnect the hard-drive interface cables:
a. If SCSI hard drives are installed, disconnect the interface cable from the controller card.
b. If SATA hard drives are installed, disconnect the interface cable from the SATA_0 and SATA_1 connectors on the daughter card. See Figure A -3 .
9. Remove all PCI expansion cards installed on the riser card. See " Removing an Expansion Card " in "Installing System Components."
10. Remove the riser card. See " Removing the Riser Card " in "Installing System Components."
11. Disconnect the chassis intrusion cable from the INTRUSION_SWITCH connector on the system board.
12. Disconnect the two power cables from the 12V and PWR_CONN connectors on the system board. See Figure A -3 .
13. Loosen the captive screw that secures the system board tray to the chassis floor. See Figure 7 -3 .
14. Using the tab on the system board tray, slide the system board forward (toward the front of the system) and lift the assembly up and out of the
chassis. See
Figure 7 -3 .
15. Lay the system board tray down on a smooth, nonconductive work surface.
Figure 7-3. Removing the System Board Assembly
CAUTION: Only trained service technicians are authorized to remove the system cover and access any of the components inside the system.
Before performing any procedure, see your Product Information Guide for complete information about safety precautions, working inside the
computer and protecting against electrostatic discharge.
NOTE: As you remove the memory modules, record the memory module socket locations to ensure proper installation.