Supermicro's web-based IPMI interface exposes SNMP under its Configuration menu. Here's how to turn it on and what it reports.
In the BMC's web interface, go to Configuration > SNMP Settings. Supermicro ships this off by default across most X11 and X12 generation boards.
Set a non-default get community for polling, and add a trap destination if you also want push alerts on fan or PSU failure rather than relying on Linivo's next poll to notice.
Supermicro's hardware MIB reports fan RPM, PSU status, and chassis intrusion in addition to the standard temperature and voltage sensors most BMCs expose.