this should put your worries to rest
2 years ago i built the rig you see described in my sig below - my first PC build.
I relied on the Asus performance monitor utility to monitor my cpu temps (core temps) and it never showed higher than 67C.
For three months i rendered video files (1 - 1.5 hour jobs), and the rendering program is a core hog, it uses all 4 cores and shows 98-100% load whenever rendering.
Then for whatever reason i downloaded RealTemp temperature monitoring utility and discovered my cpu was really running at 99-100C - i couldn't believe it, so downloaded a few other temp monitoring utilities, including intel's and they all confirmed RealTemp's temperatures. Then i found threads of users complaining of ASUS's screwed up utility, creating conflicts in BIOS etc and not reporting accurate temps.
Intel has built into the cpu thermal limiters, at 99-100C the cpu automatically throttles it's load way down till the temps drop, but it's a self protection mechanism and it must work, as since then, whenever i use the intel Extreme Tuning Utility (XTU) and let it go online to compare my results with others running the same motherboard & cpu, i am usually in the top 5%, score wise - so all those months of running it at 99-100C while rendering videos, had not done any discernible damage to the cpu.
BTW, the cause of the excessively high temps was a) i was using a crappy stock intel cooler and B) one of the plastic retaining pins had popped loose so the crappy little cooler was not even making proper contact with the CPU