A maximum power usage setting for a computing device is based on one or more of: a user-specified setting corresponding to how often a frequency of a processor of the computing device is likely to have to be decreased to reduce power usage by the computing device; an average frequency of the processor during a previous period in which the computing device was operated; a minimum frequency of the processor during the previous period; a maximum power that the computing device used during the previous period; and, a nominal frequency of the processor. When the computing device starts to use more power than the maximum power usage setting, the power used by the computing device is reduced so as not to exceed the setting, such as by decreasing the frequency at which the processor operates.