The human brain is doing the playing so we can focus on 20 watts. We can also ignore the on going visual and audio processing, complex motion planning, on line

The human brain is doing the playing so we can focus on 20 watts. We can also ignore the on going visual and audio processing, complex motion planning, on line learning, signal filtering and focus on just the Go part (in other words, < 20 watts is dedicated to Go playing). Humans also are unable to learn effectively, due to limits on attention we are not sure of yet, beyond ~4 hours per day. A talented human can reach pro level in about 8 years, enough to beat a neural net only player. The total energy use in joules spent learning is still about an order of magnitude less.