I personally run my Ryzen 5 2600 @ 3.95 GHz for 24/7 use.
I did OC it up to 4.075 GHz (stable) and 4.1 (not stable).
I'm sure it would be fine at 4.075 GHZ but because I leave it on 24/7 I just feel safer with a slightly lower OC.
And tbh the difference in performance from 3.95 to 4.075 is pretty un-noticable except on benchmarks.
You could just save a 4.2 GHz profile in Ryzen Master or your BIOS and set that when gaming and then set it back to lower clocks for everyday use.
I just personally didn't bother since that would only gain me a few fps at best.
And FYI my CPU temps never gio above 56C after 3-4 hours of gaming at 3.95 HGz and they only got up to about 60-62C at 4.075 GHz.
70c isn't big for an overclocked unit. And 1.3v is sweet. Other users have needed 1.4v to get 4.1ghz on their ryzen 2600.
But like everyone said, are you sacrificing 15c for 3 more FPS?
You gotta find the sweet spot. The lowest voltage that gets you the most noticeable boost.
Example : 3.9ghz at 1.13v
4ghz at 1.15v
4.1ghz at 1.23v
4.1ghz at 1.3
Of course, in this case, you stay to 4ghz. Gotta check the numbers on tutorials cos I put mine randomly.