Can I get help with this CPU's temps?

A friend and I have built a hybrid computer from our old computer parts. I had the casing, the psu, the hard drive, etc. And we used his MoBo, memory, and AGP graphics card. We each had a mobo, but his was infinitely better (mine was a mATX with limited expandability) but we each had the same processor--a Pentium 4 531 @ 3ghz.

We put everything together, reinstalled Windows XP Home Edition, and got it running smoothly. One day he brought the system over to my house, but once we started it up and turned on SpeedFan it said the processor was running at 105C !!! i immediately shut off the power and wondered how the proc even lived through the boot process at such high temperatures...

apparently the thermal paste seal had broken on its way to my house and that had caused the high temps

we reinstalled the fan, let the system run over night so the paste could set, and temps are still high. At idle, the CPU holds steady at 51C, and at load it gets as hot as 75C. the CPU has a thermal spec of 67.7C, so this is much too high a temp for anyone's liking. Before we sell our refurbished hybrid, we'd like some help on the CPU temp. We're using the stock fan, but the CPU is at stock speed....this shouldn't be happening. Perhaps we used too much thermal paste while installing the fan the second time?

Does it run cooler if you open the case and let a desk fan blow into it? If so, you need more airflow through the case. Most common cause is one corner of HS not secure. Often, when you push down the last corner the opposite one pops out.

Mike

Thanks everyone, I think Mike is right, because adding the fan does cool it down significantly. Just opening the case helps some. Yes, we cleaned off all thermal paste that was left on the heat sink before placing it back on. I think we'll try reseating the heat sink and hopefully that will fix the problem. If not, we'll either purchase a new CPU fan or new fans for the case.