Random overheating

[Rockenreno]

I built myself a computer about 2 months ago and it recently began shutting down at random times. After some investigation I discovered that the CPU was overheating, but randomly. Most of the time everything is fine and the CPU idles in the mid-high 20s, sometimes moving into the 30s during gaming. On occasion, however, I have found the CPU in the high 60s (at idle) and slowly creeping higher until the computer shuts itself off the save the CPU.

This can happen within an hour of booting the computer or after leaving it on for 2 days, so I am confused as to the cause. As near as I can tell it must be either the automatic CPU fan throttling, a faulty CPU fan, or some other fault with the mobo/connection. The automatic throttling seems to turn off the fan when the CPU is under 25C, but every time I've looked it has started it back up fine after the CPU temp increased. I have tried unplugging and plugging back in the CPU fan to no avail. Anyone encountered anything similar? Is there something I should be checking?

System stats:
CPU: Intel Core2Duo E6600 (with stock heatsink/fan)
Mobo: Gigabyte GA-965P-DS3
PSU: Enermax Liberty 400W
Mem: 2GB A-Data
HDD: 320 GB Seagate Barracuda
Video: EVGA 7950GT KO 512 MB

 

[Rockenreno]

I turned on some CPU temp/fan logging and the highest I've seen the CPU reach is 29C over the course of about a day.

 

[funboy6942]

That fan have the built in temp sensor like the AMD stock fans do? If so it may be failing at times not spinning the fan like it should. I would replace the fan with a "normal" one or different HSF all together and see what happens. If it has the built in temp sensor, if not I would still do it.

OH and you didnt go gobbing the thermal past all over the cpu did you, just a thin, consistent layer is all you need, and if that heat sink has a thermal pad, pitch it and get you some good paste.

 

[Rockenreno]

This is the stock heatsink/fan that came with the CPU. It does have an internal sensor, but I don't think that is failing since I am able to read the temperature through Speedfan and the program that came with the mobo, EasyTune. The Heatsink came with a small patch of thermal material already on it and it seems to have been applied to the CPU fine. I don't think that would have anything to do with this anyway since the problem is that the fan just isn't turning back on after shutting itself off due to a low CPU temp.

I just changed the BIOS setting for the CPU fan control from Auto (uses the Gigabyte mobo fan control) to Intel QST, so maybe that will help out.