Fan not detected??

[Jason25]

Hello all. A couple weeks ago, I upgraded my monitor, I bought an NEC LCD 2490. I then had to get a new graphics card to support the new monitor.. Radeon VisionTek HD2400 Pro 256MB. Everything worked fine, until last night. I rebooted my PC, Dell Dimension 4400, and the screen was black and at the top it said, "Processor Fan Not Detected". I did a little research and found this from Dell to try...http://support.dell.com/support/topi...8A0&l=en&s=gen

That didnt work. I have my tower open, and I can feel and hear the fan running.. its a normal fan sound, nothing out of the ordinary. Also, the new graphics card has a fan on that too.. could that be interfering somehow with the CPU fan? Everything seems to be plugged in snug and I dont see any visual problems.

So, my questions, what could be causing this message to come up when I boot up my PC? Could it be the new graphics card? The new monitor? Something serious?

I should mention, the fan not detected error only stays on the screen for about 5 seconds, then my pc boots up normally and everything works fine.

Thank you for your time, and hopefully your help in this matter!

[deoWo]

It can be that the Fan cooling your processor is either not detected by your PC, or it is plugged into the wrong port on the motherboard.

It can cause your computer to reboot, get blue screens, and have strange errors and occurances until it is resolved. Your computer may be working fine now, but this may affect gradually and your system may get heated.

[RoninBlade]

Do you mean that the fan is not locked up? If this is a 3 wire Processor Fan motherboard header and fan, it could be that the RPM sensor is not working. On many newer motherboards the computer will not make it through the boot process if the RPMs of the CPU fan are not detected...built-in overheating protection.

You said the fan is spinning but still you are getting the error message! I would suggest you unplug and plug the fan a few times in case any oxidation may have occured on the RPM sensing lead.

[Hardwareman]

Then you have a bad fan header on the motherboard.

If the fan is actually working but the system still freezes giving that message up you may want to run diagnostics on the hard drive and indeed the whole system if you can manage it without the system locking up. You can download the Dell diagnostics from Dell's website if they are not already installed on the system and you don't have the disk that came with the system.

[Jason25]

Well, after running the diagnosics, it also said the fan wasnt detected. So I opened the tower yet again, unplugged it and plugged it back into the motherboard, roughtly 4-5 times, turned on PC, still got the error, and the fan is NOT working. I was mistaken earlier.. the sound I was hearing was not the fan. So, guess im now in the market for a new CPU fan! I did a quick search on Newegg for fans, and found quite a few... most are reasonably priced, this is one computer part I know absolutely nothing about, so if you could suggest a decent fan for me, id really appreciate it! Also, what brands should I stay away from, and lean towards? Thank you so much!

[Jason25]

I went and purchased a fan at BB. I have it "installed" and the fan works great... has a pretty cool blue LED light. However, since this came with a different plug than the factory fan, I wasnt able to plug it in the same place, so I still get the same error, "Processor Fan Not Detected" when I boot up PC. Now that I know for certain the fan is working properly, can I disregard this error? Oh and my PC seems to be ALOT faster loading programs and web pages... I had no idea a faulty fan could slow the speed down!

[Fabian]

Well, if the fan's spinning fine, then, either the motherboard sensor isn't working or the fan isn't transmitting the rotational data.

The only way to confirm that would be to try another HSF -- you could actually do that without replacing the heatsink (plug the "real" installed one into another fan connector so it will get power; plug the 2nd one into the CPU fan connector and just "hold it" in place. Turn on the PC. See if you still get the warning.

This would at least tell you if its the sending unit on the fan, or the sensor on the motherboard.

[Hardwareman]

Straight from Dell documentation for this error;

CPU fan not detected

1. The microprocessor fan cable is not plugged in or is defective.
2. Ensure that the microprocessor fan is connected to the fan connector on the system board.

Thats all they give on the subject and there is no setting in bios as far asI can see in their docs.

[RoninBlade]

In the BIOS...light up the Num Lock, Caps Lock, & Scroll Lock keys on your keyboard (they all should be lit green) and while holding down the ALT key, hit E (i.e. ALT-E). The PC should beep once...now hit ALT-B to save changes and reboot. If this does not work then try pulling the jumper on the system board that says either: CLR_EISA or CLR_NVRAM.

[Jason25]

I tried those steps in the BIOS already, as mentioned in first post... it didnt do anything. No Beep after ALT-E, and ALT-B doesnt save and exit, F10 does. Also, I could not locate anything labeled CLR_EISA or CLR_NVRAM.

I have taken 2 pictures, one of the fans connector plug and one of the fan itself. The connector plug is a 3 wire female that slides into a tiny "slot" on the motherboard. No other cords or plugs, just this one. THen one picture of the fan itself, not sure how much help this will provide, but thought id show anyway, yes, I know, fan is pretty dirty.

Connector...


Fan...


This fan does NOT work at all when its plugged in and PC is powered ON. The new fan works as it should, but is plugged into the P8 plug, which is different from the factory plug for the fan, so the slot for the factory plug(pictured above) is not being used.

With what little understanding I have of this problem, by the sounds of it to me, maybe the plug slot on the motherboard isnt sensing or detecting the plug when its plugged in?

[Jason25]

Well, appears this thread has died... thank you to all of you that posted and offered your help! I appreciate it.

[The Edge]

Dont worry Everything Is Normal . As You are Not Connecting Your Fan on Standard Motherboard connecter. Therefore the Fan Is Not present according to the your system and it is giving you error messages . but you know well that you fan is connected so dont worry about. and if you want you Remove This Error Message Go Into Bios "Disable CPU Fan Detection" this may Help In Removing Your Error message . Do Tell me What Happen Waiting for Your response

[Damiano]

When my system had a problem, it was the second fan! My board not only had a processor fan but it also had a very small bios fan. If either fan slows down, the system will shut down. If you are sure that you are using the correct jack and you are using a fan with 3 wires, not 2 (3 wire fans has a ground, positive 5 volts and a sensor wire to tell the board the speed of the fan) then you have a major problem. Your motherboard has a circuit that is designed to prevent the system from running without proper cooling. Even with a new fan, if the circuit is malfunctioning -- YOUR DONE

[Jason25]

Dont worry Everything Is Normal . As You are Not Connecting Your Fan on Standard Motherboard connecter. Therefore the Fan Is Not present according to the your system and it is giving you error messages . but you know well that you fan is connected so dont worry about. and if you want you Remove This Error Message Go Into Bios "Disable CPU Fan Detection" this may Help In Removing Your Error message . Do Tell me What Happen Waiting for Your response

Thanks! I will try to disable the warning. Ill just play it out and see what happens. If sht goes wrong, then Ill have my excuse to get a better system. Besides, I need a faster PC for my photography business anyway.

Thanks again! If it craps on me, Ill let you all know! LOL