I’m asking specifically for an Intel Core i5 processor.
For every 20 degrees C increase in temp. Cuts a silicon semiconductors life in half. So the cooler the better.
More than 75 degrees Celsius at load is a bit unusual. Anything above 80 degrees Celsius is likely a sign your cooling is not working as well as it should. With that said, these processors should shut down well before they take any permanent damage.
Intel processors have built in hard limits where they start throttling if they get to hot. For desktop and server processors this is 150C. I believe the limit on laptop and mobile processors is in the 105C range for newer processors. For more info on monitoring software to find the actual tempertaure look at http://mobileoffice.about.com/od/laptopstabletpcs/f/how-to-check-laptop-temperature.htm However if your processor is getting that hot then you have other issues which may be as simple as blocking the air vents. The cooling system made of a heat pipe and heatsink setup is not removing the heat properly. If the system is under warranty I would get it serviced. If not I would find a service manual for your model and take it apart carefully and document the process with a camera for later reference. Then replace the thermal grease on all contact points. If all goes well when you are done you will see the temperature go down a fair amount. Laptop manufacturers use thermal pads instead of grease due to it being easier for assembly but it does a terrible job of removing the heat. If you need additional info or help finding a service manual let me know your exact model number which should be on the bottom of the laptop. Good luck.
in mu opinion, the temperature should not exceed more than 65 C or 70 C. be careful, it may not only harm your system but may cause fire.
Intel® Core™ i5-2500 Processor
(6M Cache, up to 3.70 GHz)
The case temp is 72.6 C
maximum Tj max set 105 C
Intel® Core™ i7-600, i5-500, i5-400 and i3-300 Mobile Processor Series
in practical 95°C on Sandy Bridge and 102°C on Ivy Bridge you will notice the shutting down mechanism (cpu throttles its frequency and/or automatically shutdown pc to avoid damage)
The maximum temperature specified by Intel varies by generation but in general it's between 100-105°C (maximum core temperature).
Given the inaccuracy of chipset and software readings I would say as long as it's below 90°C you are fine.
Usually it's the other components in the laptop you should be worried about e.g. the graphics chip, north- and south-bridge or the hard drive.