I cant figure it out. My CPU (PhenomII quad core) is idling at 77C at idle at this very moment.
Two weeks ago my PC started shutting down under any load. I checked and saw the CPU fan had stopped spinning. So i bought a new one, along with a new PSU (my old one was loud) and some thermal paste. With the fresh paste and a working fan it is still reading the same temps as before. Hmm.
Also, when i hold my hand on the heat-sink, it feels quite cool. Something is broken. Something has gone wrong. *** if i know. But - you know, internet. You always know.
I'm going to venture perhaps too much thermal compound and/or faulty HSF fitment (the first things that come to mind). Are you currently using the stock heatsink fan? What case are you working in and what is your airflow configuration?
I'm going to suggest adding an additional fan at the back to help expel the heated air from the case. Did you clean off and reapply thermal compound or just 'clean up' the existing stuff. I'm going to recommend cleaning off completely and reapplying the thermal compound here also - grain of rice sized dot, let the HSF spread it. There isn't protector plastic still on the HSF base (would hopefully say remove before installing) is there?
Putting the case side on with a fan at the back should take care of any airflow issues.
I cleared off the old thermal paste completely before reapplying, yes.
The airflow in my case is plenty. The fans keep it very cool, along with the side panel removed.
Lastly, getting my temps from Core-temp program.
You can run Speccy, available free which will tell you everything you might want to know about your computer's hardware configuration (for future reference).
It may be that the previous overheating had 'locked' your thermal sensors and they are just now becoming active again (hence, it showing proper temps now). Something I had read about thermal shutdowns stated that one recovery method involved freezing the mobo to reset the thermal sensors (I am not sure of the validity of that). Keep an eye on the temps, as long as they seem stable, I'm thinking you should be alright.