Hi!
I have same problems here. Specs:
R5 1600 stock cooler
ASUS X370 PRIME pro bios 6012
Corsair LPX CL 15 3000mhz running 2666mhz
I am only able to manually increase the voltages to 1.3125V and 3.8ghz and it passes AIDA64 without crashes and temps being ~75. Only problem is when i boot my PC like after few hours it downclocks to 1.5ghz in windows, but when rebooting to BIOS it boots back to 3.8. Also wondering why I can't raise the voltages since i've seen ppl to OC their 1600 with stock cooler using vcore 1,35 and above. Is it a bad chip or is there somekind of a overcurrent problem.
Now im running at 3.7ghz and the vcore set to auto and the temps is around 65.