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The fan went out on my 3 year old Dimension 8100 Pent 4. After two weeks of calling Dell and begging a replacment, I was finally told this morning the part is no longer made or supported!!

I went to my local Frys to look at fans, but they did not have one with a plug that would fit my motherboard. So, I bought one that directly ties in with my power source. The fan works great, but since the motherboard was bypassed I still get the message "Alert! System fan no detected. Strike F1 to continue, F2 for Setup".

Is there a way I can alter my Bios to stop looking for a fan, so that I can get rid of this alert message everytime I boot my PC?

Thanks in advance for any advice.

Is this the fan on the processor, or a fan for the system case? If it is one for the processor, you can get hundreds of suitable aftermarket alternatives from PC component suppliers.

Have you still got the old fan? You should be easily able to cut and join the wires on both to use the old plug on your new fan!

If it IS a processor fan, the last thing you want to do is disable the alarm warning! If it is a case fan, there should be an option in BIOS setup to disable the warning. Look under a 'Power management' heading, a 'PC Health heading or similar in BIOS setup. (I'm unfamiliar with your Dell, but most systems have such a setting)

But basically, I think you've simply shopped in the wrong place! If you've no specialist PC stores nearby, look for online PC components vendors.

If I'm to have the similar problem, i'd rather cut the old wires from the busted fan ang put them on the new one... but yes, as catweazle have said, there are tons of replacements around. I'm sure you can even find used ones, it's just a matter of how and where to find it...

Thank you both for your responses and advice.

This fan is for the processor. The plug receptacle on the processor is smaller than standard, and the female plugs I have found at local Compu USA and Fry's stores do not fit into it. I've been told by employees at both stores that Dell is different from everyone else. :( I've been keeping an eye out on Ebay for a used one, but so far no luck.

I do still have the old fan, and the idea to splice the old plug to the new fan occured to me...however the wire colors are different. Old Dell fan is black, red, and white...while the new fan is black, red, and yellow. I am ignorant on these matters...can I splice that white wire to the yellow or does the color difference mean different voltage?

Thank again for your help!


I think you may have different voltages there, as the BIOS might have two fan speeds, and supply this amount of energy or that amount of energy. I would guess that the black wire is negative (-), and the other two are positive. Without a volt meter, or specific technical documentation, you are stuck.

You might have the idea of checking the power with the computer on, but if you short something, that could sizzle something else. Only proceed if you really know what you are doing with the VOM, and have a steady hand.


Contact Dell support to be certain if you like, but you can be sure that the 3 wires are:

12v Power
fanspeed signal

That's not a technical description . I'm np electronics technician, I'm afraid, but that's simply what the wires do. I'd be almost certain that the white wire is for fanspeed. The red and black would be carrying the current, I'd believe.

But like I said, if you want to be certain, contact Dell's support section and ask them. You'd be surprised how helpful the response to a polite request can be at times. I was recently seeking information about adapting a particular processor fan to a front monitor/controller unit of a different brand, and ended up being sent the design reference documents for the product!

I'll follow your advice and contact Dell about the wiring.

Again, much thanks for the input and advice I've received from all of you.

just guessing that your dell is detecting the lack of a fan by an open circuit.. use one or two jumpers and a diode or a led and viola! a closed circuit and no strike f1 crap anymore haha. make sure it doesnt push too much current though or else youll have a structure fire on your hands..

I had the same fan problem with the Dell Dimension 8100 (P4 1.3 GHz) PC (System fan not detected). I bought a DYNEX (Blue LED CASE FAN) from Best Buy for $11.99 and spliced the wires (white,red & black) directly to the original MOBO fan connector. I also added an ADAPTEC PCI-mounted case fan. Now I have the CPU cooling fan and an additional fan to expel hot air from inside the case to out. It's working great. My PC has never performed better and the error message no longer appears!!

Hope this helps!!



Great post! --alc6379

I had the same issue with a Dell Dimension 8400 - the fan drove me nuts! I bought a Zalman quiet fan and realised that there was more to it than this as Dell are a bit individual. After searching for ways to turn off the bios fan error i came up with zilch. It cannot be done.

I eventually realised that I needed to work with the Dell fan. The Zalman quiet fan was shipped with a cable that had a resistor on board to reduce the voltage. I simply added this to the Dell fan red wire to reduce the dell RPM! Silence! My fan is cooling, no errors and I can work in peace!!!

Took me 3 weeks to sort this out and the solution was a 10 minute job!

j :eek:

Would you please tell me the value of the resistor you installed. I have the same problem with a Dell 8400. It is frustrating that Dell insists on a proprietary connector for the CPU fan.

Thank you.

I had the same issue with a Dell Dimension 8400 - the fan drove me nuts! I bought a Zalman quiet fan and realised that there was more to it than this as Dell are a bit individual. After searching for ways to turn off the bios fan error i came up with zilch. It cannot be done.

I eventually realised that I needed to work with the Dell fan. The Zalman quiet fan was shipped with a cable that had a resistor on board to reduce the voltage. I simply added this to the Dell fan red wire to reduce the dell RPM! Silence! My fan is cooling, no errors and I can work in peace!!!

Took me 3 weeks to sort this out and the solution was a 10 minute job!

j :eek:

My Dell Dimension also has this noisy fan, so I bought a ThermalTake "Hardcano 13", to control the fan speed.
I didnt know about the bios problem, but I will also consider a resistor solution.
The hardcano has also a flashreader, which should be connected to an internal usb connector, which Dell doesnt have, so im about to create an external to internal usb cable for it.
- It is a hard fit :( but I wont give up on this sht.. :evil:

I have connected the 4 hardcano sensors to cpu, gpu, psu and the top of the cabinet. After 3 hours of Hitman2 playing; the cpu was 42 degrees hot - which must be a pretty low temperature. Its 2,8Ghz
The gpu which is the bottom ATI X300 pcix kind without a fan, did almost reach 60 degrees before I started playing, but in the game it only moved between 65 and 69 degrees - the alarm threshold on the Hardcano couldnt be set higher than 70 degrees. So I guess I was lucky that it didnt reach 71 degrees, which would make the Hardcano display go red and start an audible alarm.
The system psu and system temperature was no higher than around 26 degrees - for you who use farenheit instead of degrees, I can tell you that my body temperature is 36 degrees and my room temperature is around 22 degrees.
The next thing I will do, is to find out which temperature my cpu can take, without shortening its lifespan too much. - If I for examle find out that it easily works when it is 60 degrees hot, then I will experiment with slower fans.

I've been having very loud fan problems with my Dell Dimension 8400 I bought a few months ago.

PC Specs: P4 3.4 800 fsb (model 550, LGA 775 Prescott), 3 GBs of RAM, ATI x800 XT 256 mb, 2x74GBs HD 10,000 RPM RAID 0, etc...

Except for the extremely loud fan (Delta AFC0912DE), the system's performance is amazing and I'm very happy with that. I've looked everywhere on the net and I realized there is a lot of other people facing the same problem. So I think I tried all the suggestions to fix the loud fan problem.

One of the first things I thought was changing the Delta fan for a quieter one because after all, Deltas are very famous for 2 things: their extremely high air flow and off course their noise! Trust me there are loads of both... However the Dell mother-board has this unique 4 pin connector which is not compatible with any decent silent fan.

Some people managed to solve the problem by updating the bios with the new A03 version (available from dell online support website) and also by changing a few power management settings on it. You can check out some posts on this solution of this forum:

Unfortunately, none of those solutions worked for me. So then tried the limiting resistor solution proposed by someone in a forum (xenium-uk). I tried several different values (from 1 Ohm to 100 Ohm) connected to the red wire of the 4 pin Delta fan. For instance, with a 56 Ohm the fan would not spin at all and anything lower than 11 ohms would make a lot of noise, so I after a few test I went for a 22 Ohm.

The system became nice and quiet however I started noticing it was running really hot (touching the heat-sink could fry my hand!). I could tell the cooling system wasn't doing its job properly. Concerned with stability issues and the overall lifespan of the system, I've realized that the limiting resistor was not the answer so I decided to go the whole nine yards and replace the whole cooling system.

So I started looking for quiet cooling solutions for the LG 775. I didn't want to go for water cooling since a proper kit that would actually be silent would cost at least £150. After a few days researching, several reviews, forums, etc, I've decided to go for the huge Zalman CNPS7700-Cu heat-sink. This heat-sink had excellent reviews and besides it's huge size, heavy weight (almost 1 Kg of copper), and motherboard compatibility issues, it's the best heat-sink to cool the hot Pentium 4 socket T processors (LGA 775 Prescott) silently!

However I haven't heard of anyone attempting to fit this monster into a Dimension 8400... It sounded like a crazy thing to do and I knew there would be no easy plug and play here but it had to be done. I measured my mother board and the interior of the case and everything seemed to be compatible. The dimension 8400 could take the huge Zalman 7700 Cu. So I ordered one which came up to £39.01 including next day shipping from

Once again there were some nasty surprises whilst installing the beast. Since Dell always try to do things a bit different, as soon as I removed my original Dell heat-sink, I realized that none of the fixing sockets that came with Zalman would fit the mother-board. Basically, Dell has drilled wholes in different places than the rest of the world!

It all seemed to be the end but I wouldn't just give it up so easy... I have watched enough Macgyver to know that there's always a way ;)

Below is link to a little guide with photos, etc of how I got the Zalman CNPS7700-CU to work with Dimension 8400 and also the results, etc.

I hope it's useful.

I've also been fiddling around with the cpu fan and am going to put it at the top of case and leave it hooked up to mb. Then put a Vantec Tornado in its place. Hopefully it fits in the green shroud. Dell should of been more responsible about this whole thing. Using a common fan with a common design. Proprietary is good for some things, but leave the common and small things alone. We all know that everything changes and that somewhere along the line they were going to move out the old and can't keep them on the shelves and we are left wondering how are we going keep this computer running. At least give us a new bios with the option to control the fan.
tDanzer, just wondering how the mod for your Hardcano 13 went? Bought one myself and would like to be able to hook up the card reader. I have an internal usb 2 pci card inside my Dell 8200 that I could hook it up to. BTW I have moved everything out of the 8200 case and put them in a Kingwin. Let me know please. I tried to pm you, but I need to satisfy post count.

YES YOU CAN!!! :!: :) :!:

New to the board and just joined to help out others if this is still an issue. Was working on customer's machine and the original case mounted CPU fan (Dimension 8100) sounded like a bad washing machine. I replaced with a smooth powerful but very quiet Sunon F-9925-B-R fan. It plugs into the standard power supply line. But I to was getting the same error message about System CPU Fan not detected. I upgraded to lastest BIOS XP2 (but I don't think I needed to for this!) and within the BIOS setting there is a selection labeled "Report Keyboard Errors" I turn that to "DO NOT REPORT" and BAM no more need to press F1 it goes right through. You might catch a glimpse of the error "Alert! System Fan Not Detected" but it keeps booting.

Hope this helps you guys as well...


06/20/2005 @ 6:30PM EST

I have 2 8100, both of their fans went out. To remove the error message I pluged the new fans to the power supply, and removed the outer black plastic surronding the tree pins so I could plug in the other attachment (from the new fan) to the original fan powersupply. So you will need some pliers or wirecutters to remove the plastic around the cpu fan power supply. you may also need some tweezers to fix any bent pins when your done.

Insert the new fans small attachment there and the message will no longer apear. (if you still get the message try pluging it in the other way.)

BTW. The fans I bought had 2 attachments, and I think almost all fans do. One goes directly to the power supply, the other one resmebles the orignal fans plug, exept that its shape is different.

EDIT: P.S. I have bios XP2 and turned off the keyboard error, and it would still give me the error.

I've been having about the same probelem as everybody else. I recently rebuilt my Dell Dimmension 4600 case. I didn't like the plasticy look so I hand carved a wooden one. When I was testing it, I noticed that the processer fan bearings were going out. It sounded like an electric sander was running in my computer. It had to be fixed so I ran out to the local computer parts supply store and picked up a StarTech 9.2m Fan. It's 4 pin and plugs into the PSU, not the MB. It is super quiet (in my opinion), but when I boot up it gives me the same error message as described in the first post. I've been searching for ways to disable the error message and I was about to give up. I'm having some trouble and have no idea what to do.

PS. I've tryed to use only the red and black terminals off of the MB. I got the same error message. I'm guessing, that I need to include the white wire too.

PSS. Something else that might have something to do with it still returning the error while being hooked to only the red and black pins could be because the old fan was a .32ish amp fan and the new one is a .13ish amp fan. If i put in the appropriate LED to increase the amperage would that effect it differently?

After many hours of thinking about how to fix my fan probelm, I FINALY found a solution! I took the red wire from the mother board strait to the + (red) on the fan; put the black to the - (black) on the fan AND the - on a LED light; put the white signal wire to the + on the LED light.

Sorry, If I troubled anybody here. I hope this helps somebody else out with the same or similar problem.

I will not hold any responsibility for damages to your system if you use my methods of getting past the error.

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