uh, thats a hard question why u cant do it... there are many voltage regulators on your motherboard, not only one take responsibily on your cpu overclocking performance, i know this is an odd example, but my i7 7700k can reach 5,5 ghz without problem.. but i have to set 9 value at voltages to get this result.. mine cpu is relided one, (i did the relid : ) )the temp is 65C at 5,1 ghz with 100% load after 20 minuntes aida64 stress test (avx off), my room temp is 29C
i mentioned that my cpu is relided... here a short tutorial vidio from delid-relid, if u dont know what is it!
https://www.youtube.com/watch?v=8fs43OyeUyU
relided cpu-s are good things but dont do it, realy dont do it!! its an expert object! intel cpu-s have extremly weak paste between ihs and cpu die but amd has pretty good one!
befor delid my 7700k had 85C under 100% load with 4,8 ghz, after delid i had 55C at 100% load with 4,8 ghz!
7700k rule:
stock 4,5 ghz = 1,2 V
4,8 ghz = 1,265 V
5 ghz = 1,315 V
5,1 ghz = 1,340 V
your voltage increasing curve should same at ryzen too
my advice is do some research on the internet!
u should hit 4 ghz at 1,38 volt