Cpu temp fluctuating.

thefinalstage

Hi,

Some of you may have noticed my other thread (with the same set up, a reseat with as5 attained a 10c drop, pretty good ).

With this new reseat when the processor is idol the temps vary between 21c and 29c, it does this constantly. Is this normal? It seems to stabilise when the processor is under load.

Prime95 running for 1 hour gave me a max temp of 55c. I am just curious about the idle temps....Could it be a program running in the background?

Inspector Gadget

It could be SpeedStep or some related CPU speed throttling technology. Otherwise, it could be some process on your system that's running periodically that's causing a CPU usage spike. Or both.

Komplett-Tech: Ryan

Its perfectly normal. Ambient air temprature in the room you are in will cause the biggest fluctuations.

Inspector Gadget

Hmm. Well, really, it depends on how quickly the temperature change occurs. If it's happening over the course of a few seconds, the only heat/cold source capable of causing that sharp of a spike (if we assume that the case isn't open and that there isn't a heat gun, freezer spray, a very large fan or some such involved) is most likely either the CPU and/or fan speed control related.

If it takes place over (say) 30 seconds or more, it's possibly in reaction to ambient air temperature changes, but only if the airflow through the case is sufficient to move most or all of the mass of air inside the case over that time. And the fact that it's heating and cooling suggests that ambient air temperature changes are not the cause; the amount of energy required to change the temperature of a room-sized mass of air by 8C is significant, and the likelihood of trying to repeatedly heat and cool by such an extent seems a little unlikely; not only that, but anyone in the room would easily notice such a wide temperature variation themselves. But having said that, it's not impossible.

It's possible that there's some error in the temperatures being read, especially if it's an analogue sensor or uncalibrated, which may account for some or all of this fluctuation. Assuming that there actually is a temperature fluctuation, I'm going to suggest one or both of the following two possibilities:

CPU usage spikes, as previously mentioned. The thermal inertia of the cooling system will soften out many short sharp spikes, so a rise of 8C would require a fair burst of power consumption over the course of a few seconds to register as a temperature spike. This would depend on how beefy your cooler is though.

Another possibility is fan speed management. If your motherboard (or Speedfan, or some other tool) is manipulating the speed of the cooling fan to keep the noise down using temperatures as a guide, then it could be "hovering" around a desired temperature - perhaps 25C, half way between 21C and 29C? Changing the fan speed can significantly change the thermal resistance of the interface between the cooler's surface and the surrounding air (slower fan = higher thermal resistance = slower heat transfer, and vice versa) and could cause the kind of fluctuations you describe if the fan speed control isn't fine-grained and/or reactive enough.

Either way, as Ryan said, I wouldn't worry about it. Hope this helps,
Gadget.