Well, I have spent the better part of two evenings trying to figure this problem out. I've come to the experts for suggestions.
I leave the PC running for most of the day and haven’t had any problems for 3 weeks. Just recently, the PC will be idling (or at the most will be downloading torrents) and from time to time, Asus Probe and Speedfan will report that the CPU Core is at 90 degrees. The times that I have been able to catch it, the temperature seems to rise from 42 (idle temp) degrees to about 90 degrees celcius in about 30 seconds. The PC is not under load, because the V-step feature has been enabled and I can see through CPU-Z that the core and multiplier have been clocked down from 2.4 to 1.6 and 9 to 6 respectively.
I also have the RAM under clocked to about 800MHZ (until I figure this out)
My motherboard temperature hovers around 35 (consistently) and I don’t have any reason to suspect its airflow. When the problem does occur, I open up the case and feel around to see if any components are hot to the touch – none are. The CPU Fan Heatsink and Chipset Heatsinks are all cool to the touch.
Performance is not hindered and everything seems to run just normally. I have Q-FAN enabled and the FANS don’t increase in speed.
Once I reboot the computer, the temperatures return back to normal. I just don’t understand it. Any suggestions would be greatly appreciated.
Antec TX 640B Case (Similar) – Older Model
2 x 80mm Silverstone Chasis Fans (Front Side Panel) – Taking Air In
1x 80mm Silversone Chasis Fan (Side Panel) – Taking Air In
1 x 80mm Silverstone Chasis Fan (Back Panel) – Exhaust Fan
1x 120mm Thermaltake 5.25 HD iCage – Taking Air In.
I have followed your suggestions and all checks out. In fact, the fan and heatsink are in there very tight. I had to work really hard to get both clips clamped down. I have also checked that there was enough thermal paste. All looks good.
Now that I think about, I doubt its a heatsink problem - since the computer can run for hours without any problems. Most of the time it will behave - it just happens occassionally, about 5% of the boots.
I am starting to wonder if its a problem with a motherboard sensor.
I've seen other people having similar problems with Speedfan, but it doesnt explain why Asus PC Probe would experience the same thing. Could it be Vista?