Fan runs at high RPM for no apparent reason

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Sony Vaio Desktop VGC-JS320J

E5400 dual core processor

The fans on my desktop are loud and running at a high RPM for seemingly no reason.

Here is the history of the problem.

Initially, when I booted the computer, the fan RPMs were at about 2200 RPM. After about 3 hours the RPM were at 3,800 but the temperature of the cores remain at 36 and 38.

I don't do anything that taxes the processor. Just surfing the internet and using Microsoft Word.

I sent my computer back to Sony. They replaced the fan. The problem has become worse.

Now within an hour the RPMs are up to about 3,800.


Someone suggested changing the settings of Smart Fan in the BIOS. Does anyone know how to do this? When i go into the BIOS there are no options to change any fan settings. It just has a setting for the two fans. They are both at around 2,200.


I downloaded SpeedFan, but when I click on "Configure" and "Fans" there are no fans listed.

I am using HWMonitor to obtain the fan readings.

In Windows, 7, I am using the "Balanced" power plan.

First off what bothers you more. The fans staying the same speed. Or the speed changing ? if you don't mind the same speed put on High performance. This might fix the problem. The other thing you can do is get a small desktop fan and pointed at the back of computer. I noticed that it's an all-in-one computer which means you can not swap out a new case.

Is it possible the room temperature changed? I used to have an AMD system that would heat a small room up significantly, though it was hard to notice at first because it was gradual.

Hence why I love refrigerated cases. Still have fans in it, but you KNOW that your PC isn't frying. In fact i am weird, I cant fall asleep unless I hear either my PC fan OR my AC.

My BIOS has an option for "fan speed controlled by SMART". Are you sure you do not have something like that?

I'm guessing that it is the CPU fan. Whats happening is that when cold its running fine, but as the machine heats up the interface between the CPU and heatsink is not transferring heat quickly enough.

At that point, the fail safe will disregard the settings and run the fan as fast as it needs to.

Basically:

Poor contact between the surfaces. The cooling unit may not be mounted firmly with surfaces in good contact. The mounting bolts may not have even pressure or may have come loose. They may also be too tight. There is a thermal paste situated between the the fan block and CPU to facilitate heat transfer. It may be insufficient or dried out.

Solution. Have someone with experience remove the fan, clean the old paste and apply quality new stuff. Arctic silver is a nice product. Remount the cooling unit correctly. Consider that it may be insufficient for the job. An after market CPU fan will cost you about 30 dollars, but you certainly could go higher(though I never have). Lately I have been using rocketfish fans. They seem nice and quiet.

When hunting for a fan(if you do), the size of the fan heavily influences its average speed, larger being better.

Summary:
Replace thermal paste. You are going to have to do that anyway when removing the CPU heat sink. time: about 1 hour for a tech. Labour: free? Or what ever local techs charge.
Swap to a better grade of fan. time: inclusive with changing the paste. Cost: 30-40 dollars tops.

Additional point of interest: aluminum and plastic cases are noisier than steel ones. Good quality cases are quieter. (Mine is particularly.... aluminum).