TJMax is written into each core by Intel so I'd trust that as a starting point. Hitting the Defaults button in the RealTemp Settings window should reset it to the default TJMax. RealTemp reads that value OK.

The slope error in these new sensors is much greater than the slope error in the 45nm Core i7 series. You would need to get your core temperature up to about 70C before slope error becomes a non issue. Most of the difference from core to core at that point is error in TJMax.

The easy thing to do is to run Small FFTs until the temps stabilize and then add on a few degrees to the center cores until the temps across all 6 cores are fairly well balanced. It will make things look nice if nothing else.

It's too bad that Intel has taken a step backward with these latest sensors. With 6 cores and 12 threads at 4.5GHz+, there probably won't be too many complaints.