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Table 4-10 POST error messages (continued)
Screen message Probable cause Recommended action
521—Memory fan (3) not
detected
Memory fan(3) missing, disconnected,
or defective.
1. Reseat the fan cable.
2. Reseat the fan.
3. Replace the fan.
522—Memory fan (4) not
detected
Memory fan(4) missing, disconnected,
or defective.
1. Reseat the fan cable.
2. Reseat the fan.
3. Replace the fan.
523—CPU fan (2) not
detected
CPU fan(2) missing, disconnected, or
defective.
1. Reseat the fan cable.
2. Reseat the fan.
3. Replace the fan.
524—Rear chassis fan(2) not
detected
Rear chassis fan(2) missing,
disconnected, or defective.
1. Reseat the fan cable.
2. Reseat the fan.
3. Replace the fan.
525—Front chassis fan(2) not
detected
Front chassis fan(2) missing,
disconnected, or defective.
1. Reseat the fan cable.
2. Reseat the fan.
3. Replace the fan.
526—CPU Liquid Cooling
pump not detected
Liquid cooling pump on CPU1 is not
detected.
1. Reseat the pump cable.
2. Replace the pump.
527—CPU Liquid Cooling
pump (2) not detected
Liquid cooling pump on CPU2 is not
detected.
1. Reseat the pump cable.
2. Replace the pump.
528—CPU requires Liquid
Cooling solution
Invalid system configuration. 1. Remove incorrect processor and reinstall original
processor.
2. Remove incorrect cooling solution and reinstall
original liquid cooling solution.
529—Unsupported WiFi
Device(s) Detected
An unsupported WiFi device has been
installed into an internal slot.
Remove the unsupported device.
917—Front Audio Not
Connected
Front Audio mechanism is missing or is
not connected.
1. Replace or reconnect the missing front audio
mechanism to the system board.
2. Reseat or replace the missing mechanism cable.
918—Front USB Not
Connected
Front USB mechanism is missing or is
not connected.
1. Replace or reconnect the missing Front USB
mechanism to the system board.
2. Reseat or replace the missing mechanism cable.
921—Front USB Not
Connected
Front USB
mechanism is missing or is
not connected.
1. Replace or reconnect the missing Front USB
mechanism to the system board.
2. Reseat or replace the missing mechanism cable.
156 Chapter 4 Diagnostics and troubleshooting