In my experience with various i7 CPUs, even a 10-degree difference in core temps under 100% load is not unusual. I have four of them running the BOINC client software which pushes 100% 24X7 and I've yet to lose one due to the heat. As long as your hottest core is not beyond whatever limits you have decided upon I wouldn't worry about it. To me, running high-power CPUs in cases as small as Shuttle Cubes, if they are under 90-degrees under load I don't give it a thought.