AMD 45nm median voltage limits:

[chew*]

1.475 is max i would bother with most chips for 24/7. TBH if I had the time and ripped my rig apart and put the amd system in thats been waiting for quite some time, I would be happy with 3.6 24/7, then again my 24/7 pc is mission critical, Quiet and cool.

The point at which is takes excessive voltage for minimal gains for 24/7 use is the point that you will degrade varies chip to chip but 1.475 is preety much safe for all chips.

Best way to find out is to remove the buffer (IHS) run on cool water at a max prime stable speed.

Let water get room temps then boot. It will instapop the chip think that happened at 1.5v IIRC but not 1.475 with quite a few test candidates.

If you can instapop, then it's fairly safe to assume you can degrade with the buffer in place.