Dell Inspiron 9400 CPU fan replacement

Posted on 2009-05-16
Last Modified: 2012-05-07
I am helping a friend who is haing problems with a Dell Inspiron 9400 laptop computer.  When I got it, Windows would not boot and the numlock and caps light would blink for about 20 seconds followed by the computer turning itself off.  I did find ino that pointed to a memory problem.  I replaced the memory and Windows will boot now.  My concern now is this.  When I powered the computer on, I turned it over and noticed there is a grid on that covers a fan that does not turn.  I believe that it is the CPU fan.  If I blow canned air into the opening, the fan does rotate.  Should this fan run any time the computer is on or should it run only as needed?  Was this the cause of the memory failure?  If the fan should run continuously, what could be wrong with it since I can rotate it manually?
Question by:persegal
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Assisted Solution

ddanonimity earned 100 total points
ID: 24403207
If you look into the bios it may show under something like power management settings, the setting for the CPU fan. Also you can have a look what temperature the CPU is running at in the bios. If it is running a low enough temperature while the fan is not turning then it is probably OK, and will kick in when it gets warm. To test this you could try putting a DVD in and setting it to boot from DVD. On most laptops I have encountered this usually makes the CPU fan kick into overdrive. If that doesn't work try watching a dvd on the computer. Display DVD video should definately activate the CPU fan
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Expert Comment

ID: 24403212
Normally fans in notebooks only run when they reach a certain temperature. They also run at different speeds, depending on the heat. It also depends on the processor used. Many cheap notebooks that don't have a CPU built for notebooks will have the fan running at full speed all the time. But Dell uses notebook CPU's.
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Accepted Solution

jamietoner earned 200 total points
ID: 24403351
Boot to either the utility partition(f12) or the drivers and utilities cd and run diagnostics on the fans this will tell if the fan is functional.
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Author Comment

ID: 24403806
Thanks for your responses.
I checked the Power Management settings in the BIOS and did not see anything about the CPU temperature.  I also brought up the utility partition and ran the diagnostics.  They ran error free anthough I did not notice any reference to fans.

Is there a Dell utility for controlling / monitoring the CPU fan and/or temperature monitoring?

The only utility I have found so far is I8KfanGUI from
It has a the following disclaimer however
By using this software you are changing the thermal management of your DELL notebook. This program is not supported by DELL, so any damage caused by this program is not covered by your system's warranty nor by me. YOU'RE USING THIS PROGRAM AT YOUR OWN RISK !

Have you ever used this utility?

I want to make sure everything is working as it should before I give this laptop back to my friend.
Any advice?
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Assisted Solution

rindi earned 200 total points
ID: 24403875
Why not just run some CPU intensive processes on the PC and check if the FAN starts up after some time. You could run an AV scan and maybe a Spybot S&D scan at the same time, this should exercise the system. You could also boot the UBCD and run memtest86+ or one of it's CPU Burn in tests from it, this also should exercise the CPU enough for it to heat up and get the fans running.
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Expert Comment

ID: 24403978
The CPU fan should run at full speed for a few moments during startup. If this does not occur then I would be suspicious of the fan being faulty.
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Expert Comment

ID: 24403988
On notebooks that's usually not the case. On Desktop PC's it is.
LVL 34

Expert Comment

ID: 24404015
I have used I8kfangui many times. The warning is for people who want to turn the fan down because they think it's too loud, then they overheat and fry their hardware, if this happens Dell won't be responsible for replacing the hardware even if it was under warranty. If you want to run a test on just fans you have to choose custom test.

Author Closing Comment

ID: 31582250
Thanks for your help.  I installed and ran I8kfangui and was able to manually turn on the CPU fan to verify that it is operational.  That sure beats taking the laptop apart to replace a part that is working.  I hesitated boosting up the CPU temperature with load as I was worried that I might fry something (like the memory).  Thanks again

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