Well, I have an i7 960 @ 3.2GHZ, not overclocked... just did some testing... wondered about this... Every core running at 100% load... and according to Everest Ultimate, I get these temps http://i159.photobucket.com/albums/...-9BAC-2468B467F60F-50561-00000248CBF3A50B.jpg is 80C safe at max load, sustainable?
Isn't it obvious? Stress testing. The procesors never rose above 82C during 100% load on all 8 cores. Noted, see the above.
You neglected to identify the cooling mechanism. Since it is not obvious, there is no correct answer possible. Stock? Good temps. Solid copper big block? Meh. Liquid? Not good. Interesting insight: http://www.pugetsystems.com/blog/2009/02/26/intel-core-i7-temperatures/