This read-only INTEGER reports the current air temperature, in degrees Celsius, at the exhaust of the power supply, returning -1 if it does not report a value. Comparing this against the intake temperature tells an admin how much heat the supply itself is adding to the airflow, which can indicate an internal fan or component problem. For example, an unusually large gap between intake and exhaust temperatures on one supply, compared to its siblings, suggests that unit's internal cooling is failing.