From Observium

LM-Sensors

For lm-sensors/net-snmp to put your temperatures in the "Temp" group (as opposed to the "Misc" group, their name needs to start with "temp"; for Observium to see the interface the name should start with "temp-" (i.e. temp-CPU, temp-System). You can change this in /etc/sensors.conf - change the label descriptions if necessary, under your specific chipset block.

For example:

label temp1 "temp-System"
label temp2 "temp-CPU"
label temp3 "temp-South Bridge"

Papouch TME

Set your thermometer name (Option 1->0 in the telnet CLI) to the sensor name you want displayed in Observium.

Supermicro monitoring

On Supermicro motherboards, install Superodoctor on your system and put the extend line into your snmpd.conf as instructed to enable SNMP readouts of sensor values.