The set button provides for trip levels to be set for fan speed or temperature. If these values are exceeded a small alarm goes off for 30 seconds. The alarm cuts off if the reading goes below the trip value or as we just said after 30 seconds. The alarm is the first sensible alarm I've seen in a while. Most alarms are more akin to a car horn with how loud they are. The Enermax alarm wasn't too much to cause your spinal column to decalcify but it was loud enough to get your attention.