Your power supply only documents an upper bound. It does not tell how much power your device actually uses. Oddly, on laptops the power supply may not even be

Your power supply only documents an upper bound. It does not tell how much power your device actually uses. Oddly, on laptops the power supply may not even be capable of satisfying the peak power consumption. There are laptops that can only go to full peak usage if they have their battery in and charged. The charger just covers average consumption plus charging current.