Proxmox VE5 on ProLiant G5 Server CPU#0 stuck for 23s

Update from my side: I found a solution but I'm not able to link to the Debian forum entry since I'm new here.
Conclusio: BIOS -> MPS Table Mode -> Disabled (not the default value). Then PVE5 works without ACPI=OFF

works like a charm, for me it was for my test server for OMV4