Can't connect to iLO IPMI with privilege level other than Administrator, while ipmitool works fine with any privilage level. But there is no problem in zabbix to connect with user privilege level to DRAC IPMI interface. There a few posts on forum with the same problem and iLO and no solution (except setting admin level). Looks like this problem specific only for zabbix and iLO.
If I set user level for iLO IPMI connection, I've got red IPMI icon in frontend and error: ""cannot connect to IPMI host:  Invalid argument". Also there record in logs like this: "Expected privilege 2, got 4"