m1ke101, first off I'm going to assume you mean a P4 1.6A. AFAIK if your p.s. is powering your Athlon 1.2 it should have no trouble w/ a P4 1.6A (given that the rest of your configuration remains the same, apart from the motherboard (obviously)). The Northwood core doesn't draw as many watts as the Athlon 1.2.