Linux – Temperature Monitoring on Dell Precision M4500

Asus changed the way of measuring the CPU temp.

Before the update it was measuring the tj.max temps, which are from the CPU core, then they changed it to the tcase temps which are the temps in the environment of the CPU. The difference of these both temps are ~ 15°C.

(German Source)

Sounds like you need to open the system, clean the HSF unit, ensure all air intakes are clear of contamination, remove the HSF and clean off the old thermal paste (carefully) from both the CPU & HSF and apply a new layer of thermal paste.

Over time, contamination such as dust will reduce the heatsink efficiency, and should be periodically cleaned - use air duster or similar. Also, over extended heating and cooling cycles a phenomena known as "thermal pump-out" forces the thermal paste to migrate from the centre of the CPU Die towards the edges, reducing the contact area between the HSF and CPU, which reduces its efficiency.

This should help ensure your system runs as desired.

Regarding your lmsensors output, take those temperature values with a pinch of salt - the scaling factors can be off by a large margin. Check the temperatures in your BIOS and you'll likely find them higher than shown by lmsensors.