Depending on what revision of the board you have, as Klosters above says, your board may not be able to give the voltage that the Celeron asks. In most cases of PCB board revisions prior to 1.12, the P2B can only give 1.80 volts as the minimum. Since the Celeron II asks for 1.5 volts, it will not boot up. Set the voltage on your slotket manually to 1.80 volts. This is a little high, but it should be fine for Coppermines. You should be able to boot up and get a good overclock once you have done this.