> if you want to use %CPU as "how much of the total available processing power is this process using", it's potentially valuable ... the available maximum clock

> if you want to use %CPU as "how much of the total available processing power is this process using", it's potentially valuable ... the available maximum clock speed depends on variables like the ambient temperature, how bust all the cores are, and how long the CPU has been boosting for I don't think the theoretical maximum clock speed is relevant to a %CPU measurement, for two reasons. First, as you note, it's subject to a lot of things that the user generally has no control over. Second, I suppose %CPU is meant to be a measure of current/real/instantaneous load -- what is, rather than what could be.