sensors reporting weird temperatures

Depending on your hardware the sensors on your motherboard need additional calibration. Unfortunately the standard values given in /etc/sensors.conf and in /etc/sensors3.conf can only give you rough estimates because of variations in your hardware.

However there is nothing that can't be set up. There are many self-explanatory notes in the sensors.conf file and you will also find additional information in man sensors.conf on how to do this.

If your really need precise values there is no way other than taking a thermometer and measure yourself for setting up the calibration. This can take hours as you need to measure at different temperatures. Such precise values are not really needed for a normal hardware setup. If you feel like overclocking then maybe you need at least calibrate the upper limits to avoid hardware damage.

If you use the lm-sensors panel applet then you also have access to a GUI to ease calibration.