Power management of an information handling system PCI Express bus dynamically adjusts the inactivity time at the bus that is determined before initiation of a low power state by analyzing the transitions between low power and operating states over time. Dwell times of the bus in the low power state are compared with an inactivity goal to determine if the inactivity time should be adjusted up, such as when the bus enters the low power state too often, or should be adjusted down, such as when the bus enters the low power state too infrequently. In one embodiment, the dwell time is the time from entry into a low power state until initiation of the transition to an operating state and the inactivity goal is the time required for the bus to enter and exit the low power state.