System vs. CPU temperatures
I tend to get a bit paranoid every time when there is an incident with my computer which might imply the possibility of damage, especially if the computer is new, awesome and not so cheap.
In the interest of cutting down on noise I turned the smart fan option in my BIOS which is supposed to make the CPU fan spin only when it detects higher temperatures. After setting it that way it seems to have been working for a while and I forgot about it until last night when my computer shut down by itself a couple of times.
Second time, when I was working on it, I tried to turn it immediately on after sudden shut down and a few times after pressing the power button it turned on for a second and then turned off. This hinted me at temperature problems. And indeed, after finally turning it on, looking at the BIOS revealed a system temperature at above 80 degrees celsius, but falling.
Now, since I never was sure if the system temperature, for always being bigger on my comp than a CPU temperature was really system temperature. If it was the other way around then what I just saw was a temperature of my CPU - above 80 degree! That started my paranoia and prompted some research of the issue.
So to cut the story short, what I found out is that the way it was showing temperatures is correct. Indeed, system temperature is much higher than CPU. It is likely that the sensor is placed in some hotspot within the system (I couldn't find the sensor's exact location) whereas apparently well cooled CPU enjoyed much more comfortable temperatures. Still, I don't trust the smart fan and I wont use it again. The fan is spinning all the time now. What happened yesterday is most likely that the CPU reached 60 degrees (which is within the tolerable limits before getting damaged) and hence triggered a BIOS alarm (as it was set that way) which apparently resulted in shut down. The system temperature was about 80 because there is apparently a dependency between how hot is the CPU and how hot is the spot in which the system sensor is.
Reason why I believe CPU really is cooler than system temperature is because, for one, I couldn't make a mistake of switching connectors as I initially thought I did because there are no temperature related connectors. And second, I today started OpenArena and payed attention to the temperatures. temp2 spiked from 21 to 28 while temp1 remained at 41. Logically, the temp2 is then the CPU.
So now I'm wondering about two things. First, is anyone else having their system temperatures detected as higher than CPU? Second, where the heck are these sensors placed anyway? I couldn't find them (and they're apparently very small)? I have an additional sensor hanging on a wire that came with the case and it is plugged to the blue LCD on the case. I can position it anywhere in the case and it shows around 34 degrees right now (placed around the area close to the CPU fan).
Ah.. sorry this turned out to be such a big post.