Who cares about long term effects when you o/c? You probably just gonna use your hardware for ~6months before your hands itch to touch the new mobo again. And good luck to the next owner. I used to be a hardcore overclocker myself around 1 year ago, now had a car had no more extra $$ to spend on pc hardware, so I play silent pc instead. Do underclocking, passive cooling etc.

Sometime you don't need all the processing power at all, if all you do is browse some geeks forum asking whether overclocking will kill your mobo faster, dl some pr0n, IM etc etc. BTW, i run my Barton 2600+ at 1GHz 1.1v (stock is 1.67GHz 1.65v) heat output is roughly 18w full load. Very flexible processor since it can do 2.4+GHz on stock voltage.