I built a ystem using the Intel E8400 (3 GHz Core 2 Duo) and DG35EC Desktop MB. The E8400 comes with a heatsink with pre-applied thermal paste, which I installed correctly (as far as I can tell). When I started up the computer the first time, I was sifting through the BIOS settings and happened across a Hardware Monitor that said my CPU was running at 102 C and the ambient was 42 C. I immediately exited and shut down. I started everything up again hours later and went straight to that screen in the BIOS config - same readings. No changes while I watched (no increasing temps, for example). This seems suspicious to me for a few reasons, but I wonder if anyone can help me out.
First, the CPU temp is obviously very high and I would expect damage from the first time I booted (several minutes @ 100+C) - but everything seems okay. Second, even for a poorly-seated heatsink, that temp seems ridiculously high. Third, the ambient was way above actual - the room is ~15-17 C and I actually had the side cover off during that period. I do not notice any warmth on the heatsink or in the air around the MB. Finally, even if the heatsink were completely off, would the chip heat up so much just from loading the BIOS? I've read that the E8400 has had some temperature reading problems in the past - is that still true today?
It's a brand new computer so no OS is yet installed - I was planning to install Linux. Are you saying that the 102C reading is probably faulty (I know, you can't know that for sure) and that it might be OK to run an OS setup anyway? If you boot and look in your BIOS, what does it say the temp is? What MB are you using?
Update: After reinstalling the CPU/heatsink again, and verifying everything was as it should be, I started up, checked temps manually on the heatsink (approx. room temp) and installed Ubuntu. No problems at all. When using the lm-sensors program, I note that the fan speed is only 1700RPM, but the "sys temp" and "cpu temp" are listed as 85 and 121 C, respectively. However, core temps 0 and 1 are 24 and 25 C, respectively. An "aux temp" is listed as -73 C. So, it appears something is amiss with the sensors and/or reporting. I notice on Tiger Direct, another person had an issue with the 102 C reading from the BIOS. Anyone else have similar mis-reporting?
One thing, did you re-apply thermal compund between the heatsink and the CPU? I don't know why you have to, but it worked for me. The only problem I encountered was that to properly install the fan, you have to basically take the motherboard out.
Some things which helped was to reread the instruction booklet that came in the pack, which shows how to properly install the heatsink. There is also a video on Intel's website showing the proper installation technique.