Ethash peeks at noticeable less power than equihash on my 1060's (most probably the same for all Pascal cards).
Equihash like more core clock and that apparently cost more power then boosted memory (which benefits ethash).
Thats exactly the opposite of what I have experienced. The equihash (zec) is using less power.
Maybe in the early days of ZEC when mining software were completely unoptimized. It's no longer true, Ethash is so memory bandwidth bound that you can heavily underclock a regular 1070 without affecting Ethereum hash rate. ZEC and other Equihash coins on the other hand, scales pretty well with increased core count and clock speed.
I am in agreement that Ethash is more power efficient than Equihash. I haven't exactly compared wattage on my rigs mining ZEC or ETH but in theory, the need for higher core clock in equihash will draw more power from the GPUs compared to ethhash.
Maybe someone who has actually measured power consumption can chime in.