Anyone of you are electronic enthusiast or hobbyist here ? or better electronic engineer ! Not apllicable if you don't undertand few electronic jargons below here.
Have you ever make a DIY electronic thermometer using plain silicon diode/transistor as the temp probe ? You will have to go through tedious steps to calibrate that sensor just to get a "good enough" accuracy. Worst, if you replace that sensor even the same type/manucfacturer/batch, you'll have to recalibrate again !
Same problem apply to Intel too, anyway the CPU is made from the same silicon as ordinary stupid diode/transistor, and it is way too costly to calibrate that on die sensor at each CPU since they need to toast it at constant known temperatures hot and cold to get an accurate calibration at "EACH" CPU, so it will never be accurate, period.
Also, those what you called cool feature "Digital Sensor" ..yuck.....they are just plain olde stupid current sensing method to guestimate the cpu temp.
Making an accurate resistor in silicon wafer is easy and just use current sensing method and feed it thru the on chip A/D and voila !!!! A digital sensor was born ! :D Again its just to guestimate power consumption and dissipation.
While making a consistent/same forward voltage on every piece of silicon to detect same temp changes will be never easy, it is the law of the nature, unless they're capable of putting silicon atom by atom "accurately' to make that piece of diode temp sensor.
Now, why those 85C magic number, cause they've decided even the sensor reading is off by 10-20C, it is still considered safe as long you don't overclock, overvolt or within the acceptable ambient temp range like your dad or mom's puter, of course with the proper HSF mounted.
Just read tons of electronic components datasheet out there, almost all of those silicon based electonic components are capable to withstand an operating temp at around 100C or even higher.
It doesn't matter what methodology/mechaism you folks are arguing, if the sensor is not accurate, its useless.
Worry and want a safe long life cpu ? Then stop OC-ing or overvolting, simple as that.
