SOC should be fine all the way up to 1.25v, especially since this board has good VRM cooling. I believe any time you use XMP or OC memory on ASrock AM4 boards above SPD it automatically increases to 1.2v.
Only thing to be concerned about is that most boards seem to over-volt the 3400g when left on auto settings. How much vcore are you seeing?
We may be maxing out the capability of this ram kit. Too bad the Gskill 3200 C16 kit is so pricey.
@1.2 SOC the ram setting of ddr4-3400 1.35v 16-19-18-19-36, with all subtimings set to AUTO, 1T, geardown and power down disabled, was stable over 800% with memtest.
When I went back to tighten the subtimings windows BSODed.
I was using the new Ryzen DRAM calculator to figure out what I want to try by comparing the AUTO, 3333, 3400, 3466, 3533, and 3600 settings.
Not 100% sure keep the SOC at 1.2 is awesome for the hardware for 24/7 use and was thinking about testing the above at 1.1875 or going back to DDR4-3333 and tightening the timings. Would be awesome if we could up the Ram voltage to 1.45 though :‑X