CPU overheating or damaged?

My desk top started shutting down unexpectedly the other day only to reboot with the warning of a emergency shut down to prevent damage due to a overheating problem that needs fixing. It's a 3Gtz Pentium 4 running XP pro. I replaced the heatsink and fan about 2-3 months ago (which challenged me finding a 70mm fan). Well when replacing the heatsink and fan the old one was really on there to the point that when it came free the CPU seemed to separate! I lifted the lock arm and put it back then locked down again. I am now thinking that since the fan is working (3500rpm and 119-139degrees, is that hot?) but shutting down after less then 5-7 minutes that I actually caused damage to the CPU even though it worked and ran well until now. So, am I looking at replacing the whole board? I am comfortable working on it up to anything with a solder so I'm not sure how much I'm into. Thank you for your advice and counsel. Do I need to provide more data?
Sincerely,

did you apply new thermal paste to the heatsink when you replaced it?

yes, the new fan came with the white stuff that I applied. That was my other thought, maybe I failed to applied an even thin coat and the unit was not able to stay cool enough.

Did you clean off the old paste first?

Sounds like you may have applied to much of the new paste. Debates continue on how much\little to apply. I have always had good luck with one small dot, slightly smaller then a BB applied to the center of the processor. Once the heat sink and fan are fastened into place and the PC is used, go`s through it`s normal heat and cool cycles the paste will spread on it`s own.

To much can cause over heating problems the same as to little or none.

you know that's a possibility. My determination to get an even layer may have over done it. There is definitely more than a bb, closer to 3 bb's. Is there a danger with re-applying the paste? I did wipe the old paste off before beginning then used a plastic card to spread across surface being careful to not have it end up anywhere else. In regards to unit being yanked off with the heatsink and then put back, what damage might have been done? Am I able to replace only the CPU?
Thank you

There is a slight chance the CPU was dammaged check for bent or missing pins this is usually what happens. I can say that on numerous occasions the processor comes off with the heatsink when I replace thermal paste and I haven't had one that has been damaged yet. As ThunderZ mentioned less is definatly more with thermal paste you want the least amount that will do the job. The function of the thermal past is to fill the microscopic voids in the two mating metals allowing heat to transfer efficently if you put too much on you will do the opposite and insulate the processor from the heatsink. Also make sure the heatsink fan is running properly and that its plugged into the CPU port on the motherboard. The motherboard monitors this connection to make sure the fan is running properly so the CPU does not overheat.

i will clean off and re-apply a small amount of paste. I installed Sensorview to monitor the temps and such. I'll check the pins at the same time. What is a normal temperature for this to be running?

More info then you`ll probably ever want to know about your processor.

As noted in the info. The temperature is not only effected by the heat sink and fan but the overall ability of your case to flow air as well.

Thank you for the link. I love learning about this stuff! I went ahead and re-applied the goop as conservatively as possible and surviving a bent pin incident got lt back together and it still ran a hot 58-59C temperature. This unit stays at a steady 0C albeit somewhat smaller. I quickly shut it down and restarted it in safe mode and it is now running at 0 degrees C! So, is something running in normal mode that would cause that? Is there a log of some sort to tell me what the issue is?
Thank you,

You can try process explorer it will tell you whats running and using your processor.