Heat sink fan running way too high all the time.

[eharris]

I have a Dell Dimension 4550 (bought in 2003) and while doing routine work, the CPU fan kicked on really high (maximum speed) and stayed on at that level ever since.  I checked the whole system for viruses and there were none. 

The air blowing out of the machine is not even warm and I doubt that my CPU is overheating.  The other ventilation fan at the top of the tower is working normally and the computer functions properly.  The heat sink fan is loud and annoying.  I have scoured the internet and downloaded some programs to diagnose the temperature of the CPU, but they are all blocked saying that the Pentium 4 model that I have in this computer is proprietary.  I have taken the fan module out, cleaned everything, added new thermal grease to the heatsink and this does not solve the problem.  The fan kicks into overdrive the instant the computer is turned on.

Since I doubt the computer is overheating, I am wondering if a temperature sensor has gone out and the default for that is a fan that works on overdrive.  Does anyone know a solution to this problem or how to fix it?

[computeruler]

Try turning smart fan on in the bios, if there is an option for it.  If not, have you tried realtemp? http://www.techpowerup.com/realtemp/
The only other thing you can really do is to try plugging the fan into a different port, or getting a fan controller

[eharris]

I am at work right now, but as soon as I get home tonight I will try out your suggestions.

[westom]

I am at work right now, but as soon as I get home tonight I will try out your suggestions.

Its a Dell.  It comes with comprehensive hardware diagnostics that test fan speed.  Once those diagnostics confirm that hardware works fine (yes, one hardware failure mode is to run fans at max), then move on to find the problem in software.

  Comprehensive diagnostics boot from the hard drive, are on provided CD roms, and may be downloaded from their web site.

[eharris]

I downloaded Realtemp and that program cannot diagnose the problem due to proprietary info by Intel.
I looked in the Bios (version A08, which is the most updated for this computer) and there was no option to adjust fan speed.
I will go ahead and see if Dell has any diagnostic material as "westom" suggestioned.

[Quantos]

On a side note, I wouldn't be overly concerned by the speed of the fan.  They actually last longer at one set speed, the changing of speeds is not good for the armatures. 

[westom]

I will go ahead and see if Dell has any diagnostic material as "westom" suggestioned.

Dell Diagnostics are available here:
http://support.dell.com/support/downloads/format.aspx?c=us&l=en&s=gen&deviceid=3841&libid=13&releaseid=R64033&vercnt=3&formatcnt=0&SystemID=DIM_PNT_P4_4550&servicetag=&os=WW1&osl=en&catid=-1&impid=-1

How do I Run the Dell 32-bit Diagnostics with the Dell Dimension ...  is explained here:
http://support.dell.com/support/topics/global.aspx/support/dsn/en/document?c=us&dl=false&l=en&s=gen&docid=A2014D03404049C79D88A8FC9210B4B0&doclang=en&cs=

[eharris]

I performed every test possible with the ResourceCD and defraged the HD and everything but one issue is fine according to the computer.  One error messege did come up reading:

Error Code 0F00:131A  IDE device failed


I don't know what that means but everything else, except the fan, seems to run normal.

[computeruler]

That means some ide device, your hard drive or cd/dvd drive failed