Thanks for the important picture, may cpu is B0 stepping and the temp in ipmi is not as high as the die average, from you picture I see your CPU also high in this die average temp, so I think it's probably because of the ES stage CPU.
HWinfo sensors: CPU Die (average) is IMHO nonsense. in the IPMI sensor page is nothing hot.
If it helps... I'm running a Production Sample EPYC 7252 on bare metal here under Windows 10 1809. Noticing a similar trend with the CPU Die (Average) temp accordingly which may point to this not being an ES exclusive issue or even specific to 7452/7502 for that matter. There is barely any load on the CPU at the moment.Ok, but EPYC with windows and running hwinfo is hard to find.