I agree with you on variations with electronics, but in this case it is designed right into the CPU logic. What happened was that Intel gave up on their evolution of their then current desktop CPU designs with the end of the line Prescott, affectionately known as the Preshott, and started to redesign their mobile line of CPUs to be their followup desktop ones. They became the very popular and fast Core series of CPUs, plus the Atom for netbooks. A very wise choice. Given that SpeedStep was already built into the circuit logic, it seemed unnecessary to design out a valuable feature and left it in place. It is one of the reasons their current Core generations of CPUs run efficiently at lower overall temperatures. To the extent that variability can be an issue, it is most likely entirely offset by the lower overall operating temps of their CPUs.