(Here is a related, earlier question.)
Two microprocessors are identically manufactured. However, after testing the two processors, the manufacturer bins, rates and labels them to operate at slightly different frequencies -- for example,
whose specs differ only in the clock rate. Once the manufacturer has shipped the two processors, assuming that the customer clocks each processor at its respectively rated frequency, I've five, closely related questions, please:
- Am I correct that the faster processor draws more power (and thus dissipates more heat) under a computational load?
- If so, is the power under computational load approximately proportional to the rated/clocked frequency? In other words, inasmuch as the one processor is clocked 8 percent faster than the other, does it run about 8 percent hotter under load? Another way to ask the same question is to ask: does each processor process about the same quantity of data per unit of energy? or, if battery powered, can each accomplish about as much before its battery dies?
- When not under load, do the two processors idle equally cool, or are there practical or theoretical factors that make the one idle cooler than the other?
- Even if the processor's price were not determinate, might one prefer the slower processor merely for the sake of cooler operation and extended battery life?
- Would the answers differ for embedded processors?
Naturally, you needn't number your answers 1 through 5. If the general thrust of my inquiry seems clear, then feel free to answer accordingly. Even partial answers would be read with thanks.
The reason I ask the question -- besides that it is interesting -- is that Intel (for example) gives each of the processors mentioned a thermal design power (TDP) of 35 watts. Such information hardly helps one to choose between two such processors (or between two microcontrollers by ARM, etc.) as one hesitates between quick peak processing and cool extended operation. The question is thus a prudential engineering question that datasheets do not seem directly to address.