There is a difference between 'max' and 'absolute max' vcore.

Max = 1.3625v

Absolute max = 1.45v

If you read the portion of the data sheet I have quoted below, it states that the max voltage is the functional limit of the processor. The absolute maximum voltage lies outside the functional limits of the processor, and long term reliability will be affected to some degree with the severity determined by the length of exposure to these voltages. If you go beyond the absolute max voltage, the processor may not function anymore, or will have it's reliability severely degraded.

We know the CPU's will still function after excursions above 1.45v, however we have no idea how badly they have been damaged. I have benched my E8600 at 1.56v on air for hours with no obvious ill effects.

It should be clear that 'safe' vcore = no more than 1.3625v

2.6.1 Absolute Maximum and Minimum Ratings
Table 3 specifies absolute maximum and minimum ratings only and lie outside the
functional limits of the processor. Within functional operation limits, functionality and
long-term reliability can be expected.
At conditions outside functional operation condition limits, but within absolute
maximum and minimum ratings, neither functionality nor long-term reliability can be
expected. If a device is returned to conditions within functional operation limits after
having been subjected to conditions outside these limits, but within the absolute
maximum and minimum ratings, the device may be functional, but with its lifetime
degraded depending on exposure to conditions exceeding the functional operation
condition limits.
At conditions exceeding absolute maximum and minimum ratings, neither functionality
nor long-term reliability can be expected. Moreover, if a device is subjected to these
conditions for any length of time then, when returned to conditions within the
functional operating condition limits, it will either not function, or its reliability will be
severely degraded.