125W TDP, not necessarily 125W power draw. The heat thrown out and the power used are two different things. You are running a computer chip, not a 3 bar heater, so not all of the power will go to heat because you are using the majority of the power on processing data. The cooling system is designed to dissipate 125W of heat, the chip is able to draw much more power than this, because it isn't 0% efficient