Assuming the calculated number stands statistically, a 30% increase of Vcore reduces the 50% sample failure time to 59% (a little over half-life). The 30% voltage number of 1.95 V, 2.08 V, 2.15 V seems to fit nicely w/ the AMD absolute rating 2.05, 2.15 and 2.20 V on Vcore for the DLT3C, DUT3C and DKT3C respectively in the data sheet.
At least, based on analysis, if it stands, we can rule out the guessing numbers of 1.8 - 2.0 - 2.2 V for max Vcore flowing around and also the concern of failure within weeks or months.
Further, in conjuction with the MHz-economic gain from 10%, 20%, 30% over voltage (I have those numbers in another thread), one can pick and chose the tradeoff between MHz gain and the reduction of statistical expectancy of CPU failure time, which is still in terms of at least 5+ years away.
PS:
As far as temperature to not having additional adverse effect on chip behavior from electromigration on top of voltage, it should be below the max temperature rating of 85/90 C (for TBred B/Barton). So using a cap of 65 C is reasonable, since above which most CPU would be overclocked above the break-even point of 10 MHz/C for Tbred B and Barton. Further increase in voltage and temperature, even if it is stable, one would get very little return in MHz, but greatly shortening the expected failure time.