When starting the computer, the system fan might spin faster and become louder, and one of the following error messages might display on the screen:
- System Fan (90a) The system has detected that a cooling fan is not operating correctly. Press Enter to clear the message…
- System Fan (90b) The system has detected that a cooling fan is not operating correctly. The system will shutdown in 15 seconds…
- System Fan Speed Failure (90f) This error indicates that a problem exists related to the heat removal system.
- CPU Fan Speed Failure (909) The system has detected that a cooling fan may not be working properly.
- CPU Fan not Detected (900) CPU Fan is not detected or may have malfunctioned.
To resolve the error, take the steps from the below link on HP website:
Link: HP PCs – 900, 909, 90A, 90B, 90F Error Displays on a Black Screen | HP® Customer Support