There is only one difference between the K-AC-PS and the K-AC-PS-1400W: Fan speed. The K-AC-PS-1400W has a fixed fan speed. This is the older model. The K-AC-PS is the exact same power supply but has a two-speed fan. The speed of the fan is triggered by temperature. In all other respects they are the same power supply and meet the same input and output specifications.