In a computer system having a device and a communications link for communicating with the device. A method for dynamically managing power consumption by the computer system comprises associating a particular device identifier with the device. Communications are monitored over the communications link to determine whether the communications include the particular device identifier. A clock input is withheld from the device when the communications do not include the particular device identifier. Clock input is provided to the device only when the communications include the particular device identifier. The clock input causes the device to transition from a non-operational power conservative state to an operational state wherein the device consumes more power than in the non-operational state. A performance requirement is established for a task to be executed. Clock frequency is dynamically controlled according to the performance requirement established for the task being executed.