Did you try to load bios fail safe defaults ?
I had the same problem with Asus CUBX-E, but when I took out the sound card everything worked fine.
Also remove the mobo from the case and install it again, there maybe a short somewhere.
You'll shorten the CPUs life cycle from 20years to 10 years and that's in theory, because by that time you'll change at least on cpu.
The only real danger for the cpu is if u over-volt it, dont set the voltage higher than 1.65v because that is 10% higher then normal voltage and is in tolerable...
Your CPU is the last one from the Celeron Tualatin series, so it has almost no o/c potential, but! :) The whole tualatin series was a test drive for, then future, northwood P4 core, so with its o.13 micron process it could scale very well.
My friend and I o/c-ed my P3 (not Celeron) Tualatin...