Very glad I found this post. My DDR5 shows odd fluctuations on exactly the same sensors. I was using OCCT and HWinfo but that was dumb of me since OCCT also uses HWinfo. I downloaded the Asrock Atuning app for my asrock MB and while it has way less sensors it did show VDD staying rock steady. I also downloaded CPUid HWmonitor and while its numbers were slightly different there were no weird fluctuations. However, while carefully watching Atuning I did see MB temperature go negative for a split second. Also the +1.8V sensor showed 2.1 for again a split second, after not moving for an eternity, so I can't even fully trust the MB software. What a cluster