Even while my quad is building TenFourFox (which uses make -j2), core temperature doesn't get much higher than 60 C. CPU utilization is around 40-60% on all cores at that time. At idle (I run my system in reduced mode ordinarily to extend the life of the unit and reduce power usage), most cores are between 38 and 48 C. At full tilt it roars. At idle it's quieter than the MDD.

Note my system is in a relatively cool room with indirect sun and it can ventilate into the center of the room, so ambient temperature and ability to vent do play a role.