Each chip has its own tolerances as well as each user having their own load they put onto them. There's too many variables to give a number.
I wouldn't say "drastically" at that speed (1.6ghz) ...
but a shorter overall lifespan of the cpu is the cost of OC. Especially considering there's no way other than undervolting to control the extra temperature generated. And that's no where near having a heatsink and fan or liquid system as in OCing a pc.
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