Much less, in theory. At an imaginary hand waving level imagine the complete state of a cpu as passing charged capacitors around and occasionally charging new

Much less, in theory. At an imaginary hand waving level imagine the complete state of a cpu as passing charged capacitors around and occasionally charging new ones or discharging some. This is not all that far off of how they work... If you want to count to 7 reversibly there's an easy way involving hitting a 7 bit shift register, 7 times. In theory there's no reason to drain any capacitors per op or per the entire system, that same unit of charge just meanders down the line. Like a CCD sensor or old fashioned bubble memory kinda. The way chips are designed today that doesn't work, but insert a lot of kinda sorta in theory it could be done. On the other hand if you want to count to 7 using three full binary adders you're going to run into scenarios where two bits enter an adder (say, 001+001) and one bit leaves (result of 010), so at least one capacitors worth of charge got turned to heat. And that charging and discharging is basically wasting battery power for no good reason. And its not a lot of power for one capacitor, but you toggle a flip flop a couple billion times a second and then not-much adds up over time to a pretty hot CPU.