Max safe voltage for Ryzen CPU's?

I would rather go for guaranteed stability and long term life.  How much time would setting every core to 4.0 GHz make over the normal 3.6 XFR (?) GHz on a 1800X?

There is a certain amount of obtaining a very high overclock, really just for the sake of bragging rights.  Ultimately, in use I really doubt it makes much difference at all.

If some video took 30mins to render and instead took 27 minutes to render, really does that 3 minutes become noticeable?

To me, those 3 minutes are lost in the overall time of the task not being done in 3 minutes but neat half an hour.  I'd be out of the room, doing something else and would probably come back a few minutes after it had finished anyway.

Again, I appreciate I am doing what tends to anger me on the internet, not answering the question, but instead questioning the OP's reason why they ask the question.

So, as far as I have read there seems to be indication that for constant running 1.35v vCore (on chip vCore not motherboard reported?) is the upper limit for safe and long term use.  However, if the voltage goes up and down and core clock goes up and down, there seems to be indication that really up to about 1.45v vCore temporarily is OK.

Certainly, normal use XFR on a 2 core load up to 3.9GHz with stock settings on my 1700x tends to want to tap on 1.4+ volts, but is closer to 1.3v when all cores are loaded up to 3.5GHz.

I guess you could contact AMD directly and ask for clarification.  They seemed quite approachable when I contacted them some while back.

That's generally bad advice.  SoC voltage is usually for higher memory clocks/IMC control.  If you are after 24/7 stability, find your maximum overclock, and back down slightly till it's stable without a voltage wall.  Those values that he gave you are very very wrong, and should not be used for 24/7 usage.  You are simply at the chips limit. 

That's what we call in overclocking a voltage wall.  If there's a significant jump in voltage required for a small MHz increase, then the chip is at it's limit.  And AMD has stated that with Ryzen 1st Generation, the max voltage that should be used is 1.425v, and no more than 1.2v SoC voltage.