I'm currently using a Supermicro H11SSL-C with 256GB RAM and an AMD EPYC 7401P with ESXI 6.5U2. Since I've upgraded to 6.5U2 I get the "host hardware voltage"-error on this machine. I can acknowledge it, set it to green but after a few seconds it is popping up again.
With 6.5U1 everything was fine. The IPMI of the board itself shows no errors at all, the two power plugs are connected correctly and are green, so I think it's an error in ESXi. I've been in contact with SuperMicro, they said, only 6.5U1 is qualified and tested and I should ask VMware for help...