Know what your temperatures are and what's safe.
A cold cpu is a happy one. Monitor your CPU temperatures.
We always take the hottest 'core' as your max core temp. Never the lowest.
in my opinion, as well as that of the HWmon software, and Intel specs, these are the ranges for sandybridge.
Green is perfectly safe. Yellow is a little warm but ok.
Red is too hot. purple is dangerous. The cpu will throttle and prevent itself from dying from overheating, but you still must keep a good temperature.
0-70 Safe
70-80 Safe. Attempt to lower the temperature
80-90 Approaching unsafe levels
90-100 Dangerously hot
If your CPU ever gets into the 80s, IMO, it's getting too warm.
It is ok to allow 80-82 for the 15 minutes IBT takes to run. As a general temperature for any period of time, however, it is overly high. The idea is to have a Sandybridge system which rarely if ever exceeds 70 in normal use. It shouldn't exceed 80 in normal use. If you EVER hit 90, stop whatever you're doing and let the cpu cool to idle IMMEDIATELY. You should not allow the CPU to exceed 85 IMO.
I always try to stay under 70 max (use, ie gaming, etc) temp when overclocked. Please note that your actual use temps (ie, playing a game) will be about 5 degrees less than prime95 and 10-15 degrees less than Intel Burn Test. For example, I get about 55-65 gaming, 70-75 in prime, and 80 in IBT.