Sorry, I can't say where could be the problem...
Core 3 and 4 are fixed at 39°C, but I see strange temperatures also with cores 1 and 2; The first core show the same min and max temp of 34°C while the second core is much more fresh with a min/max of 18/23°C.
My opinion is that the BIOS is not the problem, but it's only my opinion, my perplexity is more related to the CPU, perhaps the thermal diode is malfunctioning...
Hope someone cuold give more help.