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If a PCI expansion card normally consumes more than 3 A at 5 V or 2 A at 3.3 V, it should be capable of entering a low-power mode. It is generally useful for all PCI cards to be able to enter a low-power mode so they will conform to energy-saving standards. Family experts are usually responsible for managing the power consumption characteristics of associated native drivers and may issue power commands or request power information at any time.
A card's driver may elect to ignore power switching commands issued by a family expert by returning the DriverGestalt selector 'lpwr'. Driver Gestalt selectors are defined in Table 8-5. It may also return an appropriate indication to the family expert if a switch from high power to low power might interrupt a current or pending operation.