Dell PowerEdge R430 iDRAC8 snmp OIDs for hardware

You can typically find this information yourself by looking at the SNMP MIB files provided by Dell. In your case you can find them here (found on your product download page).

In your case, the power supply table looks like it's found at .1.3.6.1.4.1.674.10892.1.600.12.1 and the disk status might be .1.3.6.1.4.1.674.10893.1.20.140.1 (I say "might" because I haven't actually verified this)

Grab a tool like MIB Browser (for Windows) or SNMPWalk (for Linux/OSX) and see for yourself.