Your temps are perfectly normal
If its an Intel chip, its a good idea to stay under 70C. the Tjmax for most desktop Intel chips is around 100C these days
Regarding that one core showing 10C higher temp everytime, that is definitely just a faulty sensor on that core.....happens sometimes, nothing to worry about. My C0 stepping E8400 also shows one core constantly 8C higher than the other from idle to full load temps
The simple reason why one single core can't be almost 10C hotter than the others is that the cores are placed so close to each other. If one core heats up, the the cores to the sides of it have to be within 5C of it.