I was playing away for over a week with the new system and no problems.
Just since last Thursday or Friday the system freezes after about 20min in either Mass Effect Andromeda or Fallout4 (only two I tested). This can be in the middle of combat or just standing/walking somewhere, but nearly exactly just after 20min.
I always use Reshade and I always test with ReLive recording (the first week I made 2-3hours long recordings without issues in Inquisition and Andromeda).
Temperatures are fine, CPU peak 75C package in HWMonitor but not sure if the readings are correct (CPUTIN peak 40C), GPU peak 50C, they are in the same loop, SYS and MB peak ~40C.
Vcore voltage max 1.550V.
MSI AMD 390X
MSI X370 Titanium
32GB Memory @ 2133Mhz (it can up to 3GHz)
No hardware was moved or changed since.
In the meantime I tried every AMD driver from 16.x to 17.4.1
I tried BIOS from 1.30 through 1.31 and 1.41 (which was since pulled)
I tried several different BIOS settings.
I reinstalled the games.
I reinstalled Windows 10 64bit with all drivers
I ran CPU and GPU stresstests without issues.
Any ideas welcome