Methods and apparatus for voltage scaling are provided. In an example, an operational limit of a processor is determined by varying a supply voltage to force a processor interrupt fault and/or a processor reset. A clock frequency and the supply voltage can be maintained substantially constant for a time duration. If these operational parameters do not force the processor interrupt fault and/or the processor reset, the supply voltage is varied again, and the clock frequency and the supply voltage are maintained substantially constant for a second time duration. The variation continues until initiation of the processor interrupt fault and/or the processor reset, at which time least one of a clock frequency, the supply voltage, and a temperature are recorded as an operational limit. After determining the operational limit, the supply voltage is adjusted to within the operational limit.