From what I understand, there are four main sensors:
As far as I know, when you use "Unleashing Mode" on any triple core processor, you lose the ability to read the CPU temperatures. However, after looking at the sensors, I noticed a 5th CPU temperature sensor that seems to actually come from the motherboard. How is that possible? How accurate is it? How can the motherboard check both the temperature of the motherboard AND the CPU?
apparently there is a thermal diode or something behind/underneath the CPU socket on the motherboard that shows CPU temperature. That temperature is not on the CPU die itself. The core temps that are no longer registering, as per your photo, are actual temp readings off each core.I have had instances where poor heatsink compound coverage would cause different readings between core temperatures and motherboard reported CPU temperatures, about 5 degrees celcius difference. For the most part those "CORE" readings and CPU readings are fairly close together. In your case though, you only have the one to go off of.
If you noticed, the "missing" core temps are under your CPU reporting tree while the other temps fall under your Asustek (motherboard) reporting tree. They are 2 different (busses I believe is the word) for temp reporting, which is why the 5th cpu temp is there, it's a motherboard feature.