From your event log it is showing that your lower critical is 500 and lower non recoverable is 300. And that your fan4 rpm drops below or equal to those settings triggering an alert. Your config shows 300, 225, 150 for fan4. I would click select the sensor config in the editor again then click Revert (this gets the config again from the bmc and saves it to the flash drive). Then select sensor config again. Let me know if the values for fan4 are still 300, 225, 150 or if they changed back to 500, 300. There could be a problem saving config to bmc.