The team's design goal was 1 watt, but the chip ended up needing only a tenth of a watt. In fact on the original testbed they forgot to wire up the power lines

The team's design goal was 1 watt, but the chip ended up needing only a tenth of a watt. In fact on the original testbed they forgot to wire up the power lines to the chip, but the processor still worked, appearing to be running on no power at all! It turned out that it needed so little power that it could run on just the leakage from the data lines. https://www.theregister.co.uk/Print/2012/05/03/unsung_heroes_of_tech_arm_creators_sophie_wilson_and_steve_furber/ https://www.theregister.co.uk/Print/2012/05/03/unsung_heroes...