a switched power rail monitor compares voltages provided by a switched power rail and a power source to detect a predetermined differential indicative of a fault at the switched power rail . a switched power rail fault is communicated to a power manager to take corrective action , such as cutting off power to information handling system components . in one embodiment , a pair of bipolar junction transistors monitor the voltage differential to send an enable signal if the differential is within limits and a disable signal if the differential exceeds limits .