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Last reply by 07-21-2021 Solved
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2 Jasper
2 Jasper

XPS 8940, Better 3rd party cooler

Hello there

I would greatly appreciate any help to find a new/better 3rd party cooler for my XPS 8940. It came with the thin and small stock cooler and is overheating the whole time. I got a i9-10900 processor with 128 GB of RAM and I need this computer to generate some GIS layers. These jobs take 2-4 hrs every time and I can see that the processor is throttling or C° 97+ all the time.

I tried the Noctua 15S but the problem is there is no space for the bracket under the motherboard. The stock fan screws directly into the chassis from above.

Thank you very much

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My bad, we don't need that backplate and just need to follow the instruction below, am I right?? thanks.


on the bottom is the motherboard > then black spacer (included in u9s kit) > then the metal bracket (included in u9s kit) > then m3 washer (not included) > followed by m3 x 16mm screw (not included) going through all other pieces and screwing into motherboard


correct, you do not need to remove the motherboard if you follow those instructions :). good luck with the upgrade! 


Having just done this, my post is above, I’ll just mention the 2 “(“ “)”shaped heat sink mounts are positioned like shown here ( they can be mounted the other way as I mounted one backwards at first and had to change it when I found the heat sink did not screw on correctly the way I had it. So they will sit like this looking down at the motherboard: ( CPU. ) not like this. ). CPU (

Having done this now I need to correct my statement:

The most reasonable connection is to use the Noctua speed control kit (NA-FC1) which plugs into the 2 motherboard fan headers, and into the fans. Speed adjustment is then controlled by the Noctua box manually. This gives no BIOS error.

The above statement is wrong. The FC1 uses one of the two motherboard fan headers (4-pin plugs); not both. One fan 4-pin plug (header) attaches to the FC1; from there you can run up to 3 fans (using a SATA cable as power for the fans). The other motherboard fan (4-pin) header will still need to be plugged into another PWM fan. 

I have not been successful running the fan(s) connected to the FC1 at high speed. I am looking into this and have an email into Noctua for help.


Will this work with a 360 watt psu?


In emailing Noctua I found out the FC-1 will not control the fan speed at High Speed - it will slow the fan, and stop it (if the no-stop button is not pushed) - but the controller will not run the fans at 2000 RPM. 

Noctua writes.. after several emails:

Right now everything heavily suggests that the problem is the motherboard. Our products defect rate is very low, and they are very reliable. Hence, why we offer a 6-year warranty. You are using a Dell system with an OEM motherboard. These motherboards often cause undefined behavior since they don't follow any specifications. ​So, what you are experiencing seems to be normal and what seems to happen is that the motherboard does not supply enough voltage for the fan to spin at its full rated RPM. 

If others using the 8940 and the FC-1 have this working I'd sure like to know.




After many emails with Jefferson at Noctura I have a new understanding of how the FC-1 works on the Dell XPS8940 (perhaps other motherboards too).

The Motherboard controls the maximum RPM of the fan, not the FC-1. You can slow the fan down using the FC-1; with the output end of the FC-1 going to the fan. The input to the FC-1 (Y-cable) go to the SATA connector and to the Motherboard fan header. This allows you to boot with no errors and slow the fan down, but you can not increase the fan speed beyond what the motherboard indicates is the MAX speed. My goal was to increase airflow from the Noctua fans, not slow the fans down. While I was able to slow the fan, I was not able to increase the fan speed beyond the motherboard dictated RPM.

Noctua writes:

The SATA power connector gives the NA-FC1 the ability to run a 12-volt fan at full speed. This ability is limited by the fact that the motherboard dictates the NA-FC1 maximum speed. Should the motherboard be running the fan at 50% (of full speed), the FC-1 will only run the fan at 50% as a maximum also.

Now, there is a work around if your intention was like mine, to run the fan(s) at a higher speed.

If the FC-1 is connected to the SATA power connector (as normal), and the other end of the FC-1 is attached to one or more fans (3 max), you can control the fan speed WITHOUT the connection to the motherboard. The SATA provides power to the FC-1, the FC-1 then controls the duty-cycle to the fan attached to the FC-1.

          *** Of course, this means, in order to not get a BIOS error, you must have a fan connected to the motherboard headers (CPU and System – as is normal) and then add a 3rd fan, placed somewhere else inside the chassis. This fan can run at anywhere from 0-100% RPM. So, if you have a large Noctua CPU heat sink (NH-U9S or similar) and have one fan on it – connected to the motherboard CPU header (as normal), you could connect a fan to the other side of the NH-U9S and control the RPM of that fan using the FC-1 – which is not connected to any motherboard header. Or you could place a fan anywhere inside the chassis connected only to the FC-1 and the SATA power plug.

Hope this helps those thinking of using the FC-1 to increase the cooling in our systems.


  1. Diante desses fatos, e depois de ler este tópico, farei um upgrade para outro Air cooler.

    Sendo assim, qual desses recomendam mais para o upgrade:

    Hyper H412R (Cooler Master)
    NH-U9S (Noctua)

Captura de tela 2021-02-14 224722.png


hi I read through all of this post but didn’t find an answer to my question. Were any of you able to install a fan at the front of the case? More specifically I’ve ordered an XPS with rtx 3070 and plan on removing the stock back fan and installing an NF-A9. I’m wondering if I would be able to fit another NF-A9 at the front or if there isn’t any space with a 3070. 

I got a model with the 10700 (non K) and I don’t plan on upgrading the cpu cooler right now because I don’t want to risk voiding the warranty



You will not have any room at all to place a fan on the inside front area of the case.  The 8940 footprint is smaller then previous generation which makes for a cramped fit once the GPU is in place.

If you plan on gaming, or doing anything CPU/GPU intense jobs I would swap the CPU fan.  You can always re-install the original if you need to turn in your PC for warranty service.  The difference in cooling is really worth it. 

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