I run mine at stock because the CPU its self seems to do a better job of boosting its self than i do overclocking, unless i use above safe volts.
It looks like this isn't quite true for higher end Ryzen 3000, and its complicated.
If a CPU core is being used but is not under high load, like the worker thread in a game it will boost that core as high as it will go, and because that core is not under a lot of stress there isn't a lot of electrical current going into it, the CPU knows this, so it knows it can pump a lot of volts into that core to clock it high, and that's what it will do, as much as near 1.5v.
Now, if you try and pump near 1.5v into a core under high stress, a high electrical current load, it will burn it out, so that core will be lower clocked with at most 1.35v.
So this is the conundrum, what do you do with your PC? if all you do is game then 1.4v should be ok, if you do encoding, rendering and / or compiling, all these are high stress loads, then you shouldn't set more than 1.35v
Some higher end ones will do 4.4 or so Ghz on just 1.35v or less, in which case your getting about the most it would boost to anyway, so it might be worth it, if you can only get 4.2Ghz on 1.35v then its probably best just to leave the CPU to do its own thing, you would get better results.
Those tmpin things are different on every board type, you would need to find someone with the same board who knows what they are, ASRock Redit, a larger forum like OC.net or the ASRock forum
http://forum.asrock.com/default.asp