A self-tuning threshold monitor is a Windows Performance Counter monitor type that was introduced in System Center Operations Manager 2007. Unlike monitors that use a fixed threshold (static monitors), self-tuning Threshold (STT) monitors learn what is acceptable for a performance counter and, over time, update the threshold for the performance counter.

In contrast to STTs, static thresholds are simple monitor types and are based on predefined values and counters that are monitored for conformity within the predefined values. For instance, a static threshold could be used to monitor for specific thresholds, such as Available Megabytes of Memory. Static thresholds are very useful for various monitoring scenarios but have some drawbacks. Primarily, there's some acceptable variation in performance of servers even when they fulfil the same role, and as such, a performance value that may be appropriate for one server may not apply to another...