@Norbury_Brook @KT66 @Grim @nickas @Fabio_B @OLiZ
@JuergenP @janosmolnar777 @T20MAN
An update - turned out to be hardware failure in both Motherboard and the processor.
After a failed service attempt and an harsh email from me, Dell concluded they will replace my entire Workstation with a new one.
And as a courtesy they are upgrading the graphics card
Old: AMD Radeon PRO W6400, 4GB, GDDR6, 2DP
replacing with:
NVIDIA RTX A1000, 8GB, GDDR6, 4mDP
Very happy with Dell’s ProSupport - it’s worth every penny, in my opinion.
Seems to be worth the trouble, after all 
Updating once more when the new workstation is up and running.