First of all, if it's server-grade hardware (not desktop), this information (temperature, voltage, fan speeds, etc.) is usually available via management board (iLO, DRAC, etc.), over SNMP or SMCLP.
On some systems, motherboard temperature can be also retrieved using WMI: https://www.netxms.org/forum/general-support/useful-wmi-queries/msg7656/#msg7656
If management board is not available and "ACPIThermalSpot" do not provide valid temperature, you can try to install SpeedFan (http://www.almico.com/speedfan.php) and sfsnmp extension (http://deve.loping.net/projects/sfsnmp/), then collect information data via SNMP.
I never used SpeedFan/sfsnmp combination, but seen some reports that it works quite well.
On some systems, motherboard temperature can be also retrieved using WMI: https://www.netxms.org/forum/general-support/useful-wmi-queries/msg7656/#msg7656
If management board is not available and "ACPIThermalSpot" do not provide valid temperature, you can try to install SpeedFan (http://www.almico.com/speedfan.php) and sfsnmp extension (http://deve.loping.net/projects/sfsnmp/), then collect information data via SNMP.
I never used SpeedFan/sfsnmp combination, but seen some reports that it works quite well.
