How many watts is the power supply of 220 V, 3a, 50 Hz? My power supply is the power supply of the computer, which is standard for Jinhe Tian chassis

How many watts is the power supply of 220 V, 3a, 50 Hz? My power supply is the power supply of the computer, which is standard for Jinhe Tian chassis

660w in theory, but about 400W in practice