74 Responses

  1. Tyson Then
    Tyson Then at |

    Alternative is this one.

    Moves more air and is even quieter. Comes with an Omijoin Adapter Set so no soldering required if splicing cables: http://www.noctua.at/main.php?show=omnijoin_adaptor_set

    I just bought two to replace the super noisy fans in my Netgear XS712T. You don’t want this switch any where near you if you hate noise.

    1. DK
      DK at |

      Tyson, I am thinking about doing the same fan replacement in my XS712T. Is it easy? Do you have any specific instructions? Would it require only 2 Noctua NF-A4x10-5V’s?

      1. Tyson Then
        Tyson Then at |

        It is very easy. In the end I chickened out because even though the fans were much quieter I was a bit concerned about the temps on my expensive 10GB switch. So I went with a totally ghetto solution. I popped the top and used rubber bands to hold a Cooler Master Notepal X3 laptop cooler turned upside down over the chipset. It’s powered by a connection to a USB port on a Synology DS212j sitting next to it. Quiet and Cooled. If I had a dremel and more time I think I could’ve come up with a neater solution.

      2. Jay
        Jay at |

        I updated mine and its been running with the fans for 3 months now with no issue. The only thing I will say is that there are 2 different configurations of the fans so you need to ensure that you get the right fan connector.

      3. DK
        DK at |

        Thanks guys. Jay, did you update your XS712T with 2 NF-A4x10 FLX’s? Was it quite easy? I just don’t want to go down a rabbit hole and end up damaging the 10G switch.

      4. Jay
        Jay at |

        DK it was real easy (once I got the right fan connector) but remember the second fane is held in by one screw. None of this is an issue and worse case you can put back the old fans if you like. My recommendation to you is to contact http://stores.ebay.com/Cooling-Shop?_trksid=p2047675.l2563 I bought mine from this guy on ebay and he was able to get the right fans and connectors for me. You can take pictures of the current fan connector and send it to him and he will let you know which fan to order. He will exchange it no problem as well in case you got the wrong one. I dont work for him or know him I just had good experience thats why I mention him.

      5. DK
        DK at |

        That’s great, thank you! Do you have a Netgear XS712T 10G switch? Just curious if you did the swap into that specific device.

      6. Jay
        Jay at |

        I did it on my Cisco 52 port. I dont think it will be any harder for the netgear as long as you kno how to use a screwdriver 🙂

  2. gregschulz
    gregschulz at |

    Thanks Chris for the great post, that gives me some ideas on how to make one of my storage enclosures quieter with a mod, not to mention my Cisco SG-200 switch and a Cisco router… Hope all is well – gs

  3. VirtualizingStuff
    VirtualizingStuff at |

    I used those fans (4) in my Cisco SFS700D made a huge difference in noise reduction. Ordered two more for SG300-52

    1. VirtualizingStuff
      VirtualizingStuff at |

      The “fans” I am referring to are the Nactua NF-A4x10.

  4. Ethan Banks
    Ethan Banks at |

    I must do this conversion. I have 2 of SG300-52s. And…now that I think about it…some other hardware that could use fan replacements, too. You’ve inspired me, Mr. Wahl.

  5. DIY Project: Replacing the Stock HP V1910 Fan with Golden Silence - Wahl Network

    […] on the heels of my successful fan swap in a Cisco SG300 switch, I decided to embark upon the same adventure for my HP V1910 switch. This time my wife and I set up […]

  6. Manfred Hofer
    Manfred Hofer at |

    Thanks for that great post. I also bought the SG300-52. It’s located at the basement so I thought it’s ok with the stock coolers, but no it’s not!

    I also found this one with 40x40x20 and 3Pins with <20dBA

    To be honest I'll check the Noctua and maybe will also do this conversation to silence!

    Thanks again Chris!

    PS: cause of you I bought the SG300-52… thanks for that! 😛

  7. gregschulz
    gregschulz at |

    FYI / Fwiw for those looking for various fan alternatives, or speeds/feeds such as db, cfm, power draw of their current fans, here is a handy site:


    If you know your current fan part number yet you dont know cfm/power/db specs or know your specs and need an alternative, this is handy. Once you know alternative parts, then you can shop amazon, newegg, etc…

    For example have found some Sunon’s that are plug / pin compatible with some of the comparable Delta Elec. fans making relatively simple.

  8. Manfred Hofer
    Manfred Hofer at |

    I bought 2 of the Noctua NF-A4x10 FLX and replaced the current one within the SG300. It was a little bit tricky because you need to change the pins from the Noctua. Stock fans have a different pin-out. Noctua pin-out config is tach – 12v – ground. After I changed it everything runs smooth except the described problem with the alarm in the Webinterface which is changing continuously between Fail and OK. This is little bit annoying and I don’t know how to fix it. Because I’m the fan of everything OK, I’m thinking about moving back to the stock fans.

  9. Manfred Hofer
    Manfred Hofer at |

    He Chris do you see in the RAM Memory logs that FAN #1 and FAN #2 failed or is it only FAN #1?


  10. GeisterFahrer
    GeisterFahrer at |

    Hello everyone,
    I have replaced both of the stock fans on my Cisco SG500-28p. My choice for replacement was the Noctua NF-A4x10 . I am much happier with the new fans except the “alert” on Fan#1 Fail. After a few days of running, even on a 90 degree day in CA, the temps seem to be holding up OK. Based on my quick research, original fans on the unit (Delta EFB0412MD) have 7.2CFM rating and Noctua (NF-A4x10) units have 4.83CFM. I feel completely fine giving up the cfm in exchange for some noise relief. In response to Manfred Hofer, the RAM log shows me Fan#1 only as the “failing” unit. Both fans are operational and it seems that it is the lower rpm that triggers this issue. However, it is kind of odd that since both fans are the same model that Fan#2 is not in the “fail” alert as well.

  11. JayJay
    JayJay at |

    So I tried this on my SG300-52port system and they must of change the layout as the fans wont fit in, they are about 2mm too thick 🙂 This is a pity as I need the quiet !! I also notice that the 3 pin connectors are no longer side by side but in a L shape.

    If anyone know of quieter 3 pin fans to use please comment. I found these online but they have a bad review in terms of relaibility. Gelid Solutions Silent 4, 40mm Quiet Case Fan.

  12. Dale
    Dale at |

    I fitted the Noise Blocker Black Silent Pro into my switch, it really is considerably quieter than the standard fan.

    NB Black has a 3 wire configuration, however with its operational speed of 3800rpm it still triggers the fan #1 fail error in the log. This, coupled with the flashing system light annoys me too!

    I’m looking into the output signal of the hall sensor for the tacho (I think that is what it is) of the stock fans in an attempt to find a way to dummy this.

    Thanks for putting this info online, much appreciated!

  13. Rob
    Rob at |

    I was looking through the Digikey fan selection and came upon one made by ebm-papst which seems like a nice fit. Model 412/2 (/2 designates an open-collector tach output) is 18 dBA, 5.9 CFM, and runs at 6000 RPM which is pretty close to the stock 6300 RPM (assuming the stock fan is indeed a Delta EFB0412MD) which should keep the fan sensor happy. It comes with bare wires so you’ll have to splice it in.


    1. ErikDobb
      ErikDobb at |

      First of all thanks for the great article, it made me take the effort of replacing the fan after giving up on finding a 16+ port PoE managed switch that would make less noise. I tried the ebm-papst mentioned by Rob. Would not recommend them. Although they do not have the typical 800Hz pitched noise coming out of the stock ones, they are equally loud. Had to put the 3 pin connector on it myself (ordered at digikey) but the screw holes are too wide for the stock screws, so had trouble finding screws that were both thick enough and had a small enough flat head. The latter is important because if the screws stick out, the cover will not fit.

      So continuing my search. Meanwhile I have put rubber rings between the original fans and the casing, that somewhat reduces vibration. Would have been nice if there was room to put rubber rings on the outside of the base housing before screwing the screw in, but as said: then the cover would not fit anymore.
      I also put the switch on some damping material, further reducing vibration noise, which helps considerably.
      Will post when I find the perfect fan.

  14. Darksamus
    Darksamus at |

    I just replaced the two fans in my Netgear GS752TP with Sunon MB40201VX-000U-G99. It has a 3-pin fan running at 8k-rpm at 10cfm and a db of 12.

    I did not get any fan alarms because the rpms are high enough to not trip it.

  15. Mick
    Mick at |


    Has anyone been able to locate 40mm fans that are quieter, and dont generate the fan fail alarm?

    I am looking for some to replace the ones in my SG300-28PP

  16. Dirk Vael
    Dirk Vael at |

    Hi. Took me 2 days but have finally figured it out!

    There is a misunderstanding here about the original Delta AFB0412LB-R00 fan in the Cisco.
    The blue wire is NOT a classic tacho but rather a PWM Rotor Lock Sensor only.
    see: http://www.cwc-group.com/afb0412lbr00.html
    (the -00 extension gives its purpose away; 00 = lock, otherwise the 00 would be 50 if it was a tacho sensor)

    Connecting this fan with the plug rewired to a standard GND-12V-TACH order to a normal PC, you’ll notice the Delta fan will spin but you get no readout on the TACH pin.

    I do not think the Cisco is checking the RPM at all, it just checks if the fan is spinning or not. Hence there is no RPM readout even through console commands for this model.
    I did try with an RPM spoofer to “inject” a fake 6500 rpm signal on the 3rd “tacho” pin of the Cisco,
    (using a self built RPM spoofer, see: https://www.techidiots.net/notes/fake-fan-sensor )
    but it kept saying FAN FAIL even if simulation 10.000rpm! So this was for me proof that not only the original fan was not sending RPM data back nor that the Cisco was listening for RPM data either.

    So it is not because the Noctua is spinning slower than the original fan, it is just because the Cisco is waiting for 3.3V (on pin 2) to go low (meaning fan running). Since the Noctua is not grounding the tacho pin for obvious reasons, the Cisco thinks there is no fan present/or dead, because the 3.3V is always high (not used).

    So in the end you were almost there, all you need to do, to complete the fan hack, (next to repositioning the red 12V to hole 1, and black GND to hole 3), is to bridge the TACH pin (middle one) to the GND pin (3rd one) on the fan plug itself (using a small jumper wire).
    result: FAN OK all the time as no matter what the state of the fan is, it will always think it is running. Even without any fan present you can obtain the same OK status (not recommended though)!

    I have now 2 Noctua NF-A4x10 running (without the low Noise adapter connected, they are already silent like that!) and no more alarm from the SG300-52.

    Also note that the Cisco checks BOTH fans for failure, it is not so that it would only check for FAN #1 to determine failure, I checked both scenarios.

  17. Dirk Vael
    Dirk Vael at |

    somehow my post here vanished soon after posting it (?), so I am not gonna rewrite the whole thing, I’ll just summarize it by saying you can fix the fault message using Noctua fans by connecting pin 2 and 3 together with a jumper wire. The blue cable is not a tacho wire but just a rotor lock wire, the error has nothing to do with RPM. Now the Cisco will always think the fan is running, even if no fan is present, and the error will disappear.

    1. Manfred Hofer
      Manfred Hofer at |

      Hi Dirk,

      do you have some HowTo for this or a picture how it look likes in the end. I implemeted the fans and the first thing I had to do was to change the position of 2 pins to make the fan work.


      1. Dirk Vael
        Dirk Vael at |

        Unfortunately I already installed the router (fixed with screws under my desk) so I cannot open it to take a picture, but basically what you do is:

        Cut the Noctua cable around half length (just to save cable clutter)
        Now use the Noctua plug you just cut off, to rearrange the cables as follows:

        (so using original Noctua plug to plug into socket in Cisco router)
        cable colour coming from Noctua FAN >>> cable colour of the Noctua plug to CISCO
        1: black >> 3: yellow (originally black on Cisco fan plug)
        2: red >> 1: black (originally red on Cisco fan plug)
        3: yellow >> unused, do not connect anywhere (originally blue on Cisco fan plug)

        !!! and !!! on the plug, put a jumper cable (just 1cm of wire) going from plughole 2 to hole 3 (top side, where cables go in, not bottom side where pins go in), so pins 2 & 3 are effectively always connected (3.3V & GND)

  18. Mark
    Mark at |

    Just got two of these for my SG300-52: http://noctua.at/en/nf-a4x10-flx.html

    The best part is I didn’t even need to cut off the original fan’s headers 🙂 I just used the scotchloks included with the fan, switched around the wires in the middle, and plugged it in! This way, I have crisp silence when I need it but in an emergency situation, I can easily pop the original fan back in!

    1. Jean Goulet
      Jean Goulet at |

      People with the SG300-52 or 52P better read this before ordering Noctua fans, because we just got the wrong ones.

      In the responses to the DIY article, we can see:
      – Dirk Vael wrote “I have now 2 Noctua NF-A4x10 running” (for the SG300-52).
      – Mark wrote “Just got two of these for my SG300-52: http://noctua.at/en/nf-a4x10-flx.html

      It turns out these fans are not the same. The “FLX” is their 12V version, and the not-FLX is their 5V version. I went with Dirk`s model.

      We received the not-FLX version. We removed the SG300 from the rack and had two surprises:
      – There are 3 fans (not 2). Turns out the SG300-52P has a different fan setup. 2 fans for the power supply, 1 for the PoE heatsinks
      – The fans are Sunon 12V (not 5V).
      – Out of curiosity, I checked the Cisco web site data sheet. It claims there are 4 fans!

      The order on amazon.ca also had a problem:
      – The product title says Noctua NF-A4X10-FLX 5V Fan
      – The Item model number says: NF-A4X10-FLX 5V
      – You have to read the comments from the manufacturer to find out that they say ” I am sorry for the bad description. We can not change it”

      Wow, what a mess, there are contradictions at every step of the way.

      – The SG300-52P we have needs 3 fans at 12V, which calls for the Noctua NF-A4x10 FLX.

  19. Thomas
    Thomas at |


    I just replaced the fans in my Cisco SG300-28PP because it was too noisy. I bought 2 Noctua NF-A4X10-FLX (12V) fans. Replacing is really easy and Noctua delivers screws with the correct size. The only Thing you have to do is changing the wiring of the connector of the Noctua because the order is different. Just take a look at the colors (the colors match, except that blue of the original ist yellow of the noctua). Just pop the pins out to rearrange them (used a thumbtack). I’m happy with the result, but the Cisco now Shows the fan failure. For me that’s no Problem.

  20. Richard
    Richard at |

    Hi, has anyone had issues with the Skotchloks that come with the Noctua?

    I’m using the Omni 2 pin adapter that comes with the fan and the Skotchloks,

    I’ve pushed the wires all the way in, pressed down the ‘button’ and …Nothing

    Red matched with red, black matched with black.

    What am I missing here? Only thing that occurs is that the Skotchlok hasn’t cut the wires properly (The manual states that stripping the wires is NOT required).

    I’ve tested both connectors on the motherboard with the standard fan, and it works with both.

    I’ve also tested this with 2 Noctua fans, just in case I had a faulty one.



  21. Clive Carmock
    Clive Carmock at |

    Hi I just tried a similar modification to a Cisco SG350-28P However following both methods of using the Tacho wire and linking Tacho on the CIsco size to 0V still doesn’t stop the switch reporting a fan failure. I wonder if anyone has any ideas? This model uses original fans – Delta AFB0412VHB

  22. Clive Carmock
    Clive Carmock at |

    The SG350 models seems to use the tacho, as I see that when the unit gets warmer it tries to speed the fan up and the status light goes green.

  23. Nick
    Nick at |

    Hey everyone – for anyone with an SG300-52P – I originally swapped the fans with Noctua NF-A4x10 FLX (straight plug in, no swapping of pins etc.). Everything worked but I got the fan error message like many others.

    Randomly I was looking at the Noctua fan specs and noticed the NF-A4x20 FLX pushes more air and has a lower db level. Anyway, purchased 3 of them and swapped out the A4x10’s. Well what do you know… straight plug in and fan error is also gone!

    If you are going to make the fan swap with Noctua use the NF-A4x20 FLX. It’s a tight fit but they are plug and play.

    1. RobC
      RobC at |

      I’m surprised the A4x20 FLX worked with no reconfiguration and that the fan error is gone. Can you take a photo of the original fan connector and provide a model/part number?

    2. SeanB
      SeanB at |

      I used the Noctua NF-A4x20 FLX fans in my SG300-52P . All 3 fans were swapped out and the fans spin fine and are extremely quiet but I still get the fan error status.

  24. jo
    jo at |

    Why cut and solder? Why not just move the socket in the housing?
    Push lock in, pull out, move over, push in.

  25. jo
    jo at |

    What I meant to say. Nice post. *after reading the red box that I skipped the first time.*

  26. RobC
    RobC at |

    I just bought a pair of A4x20 FLX fans for my SG300-52 and the pin configuration was incorrect and the speed output was not compatible with the Cisco interface.

    As user Dirk Vael posted in Feb 2016, the stock fan’s 3rd wire is not a speed output. The -R00 in the original fan part number indicates that the output is a rotation detector. It’s simply an open collector pull-down that’s low when the fan is spinning and open when stopped. With this information I was able to design a small circuit for the Noctua’s speed output that produced the same behavior. I’m actually thinking of making a PCB to miniaturize the circuit to fit neatly in the case. I’ll post more once that happens.

    1. Sam
      Sam at |

      I probably should have put my request for your circuit (see below) here instead of in a new “reply” to the thread.

      1. RobC
        RobC at |

        You can find the schematic and photos here: https://imgur.com/a/YWeQS

        While the fans are spinning the signal wire produces a pulse. D1/C1 rectifies this AC signal producing a DC voltage and transistors Q2 and Q4 pull the output low. When the fans stop, R4/R9 turn Q2 and Q4 off leaving the output to float where the SG300’s pull up resistors signal a fault condition.

  27. Sam
    Sam at |

    @RobC: It would be wonderful if you could share your circuit to monitor the speed output of the Noctua. Not being an EE, I’ve searched for hours for possible solutions, but I just don’t have the necessary background to figure out what is needed. I can, however, follow circuit diagram and have breadboarded a thing or two in the past. Thanks!

  28. JanPieter
    JanPieter at |

    On the SG350-28P it seems very difficult to clear the FAN-fail error after installing a silent fan. I just installed 2x NF-A4x10 FLX fans (12V), but the rotational speedis much lower than the original Delta AFB0412VHB-AR50 fans. (Original Delta runs at 9500 rpm @12V, the Noctua runs at 4500rpm @12V.

    Simply wiring the sensor-pin-2 to GND or VCC does not do the trick. It really is checking more than that.

    I even tried to install a pulse generator (with 555 IC), this works when replacing one fan, but I could not get rid of the fan fault when replacing both fans.
    It looks to me that the circuit within the SG350-28P not only checks the rotational speed but also the current drawn from the fans….

    So in the end after doing all kind of tests it seems I have to stick with the FANs fail message… And be careful not to attach too much PoE devices to prevent overheating.

    Or maybe I have to re-test with NF-A4x20 fans, but I don’t have them available.

  29. Kano
    Kano at |

    Hey guys,

    Great info here!
    I’m having an issue. I have an SG500-52P (4 fans), and I ordered 4 x NF-A4x20 FLX’s off amazon. I reconfig’d the 3 pinout on the noctua fan by just pulling out the wires and reordering them back into the connector header.

    I pulled out one stock fan, connected the modified noctua fan, but it doesn’t work correctly. I plug in the power to the switch, the noctua fan spins up maybe to like half rpm, and then spins down to a stop about 2-3 seconds later, and stays off. The other stock fans all operate correctly.

    Anyone with any ideas? I tried 2 noctua fans so far, with both the same results. Thanks in advance.

  30. ckozlowski
    ckozlowski at |

    I’m having this issue too, using both a ESW540 and a SGE2010 (both predecessors of this switch with almost identical main boards.) I’ve been trying to replace the fans, first with identical delta models, then with new Sunon Maglevs. Despite rewiring the fans (I just pop the contacts out of the connector) I have either half-speed or no speed out of the fan, depending on where I connect it to. All fans I’ve confirmed are 12v fans. I feel like they’re underpowered somehow, but I cannot discern why.

    1. razvanphp
      razvanphp at |

      What rated power do the Sunon Maglevs have? I’ve found different versions online, so I would expect them to run slower and quieter, depends on the environment and how much PoE power you draw from the switch to keep it in a good temperature range.

      * KDE1204PKV2 0.6W
      * KDE1204PKV1 0.8W
      * MB40201VX-0000-G99 1.38W
      * GM1204PKBX-8A 2.4W

  31. Lex_France
    Lex_France at |

    Hello, I found all comment very helpfull and I found better fan in amazon.
    AABCOOLING SUPER SILENT R4 40x40x20 (6€ in France 7$ in USA).
    I don’t have any errors and now it is very quiet…
    – 3200/1900RPM
    – 7.35/4.25m3/h
    – 12.9/7.9db(A)
    – 0.09A
    – 1000000h
    For this price all other cannot do that…
    The only thing I made is putting little tool in connector to change the order of wire (it s not the same order)
    My switch is SG500-52P (4 fans)
    If you want more detail I can help you!

  32. RobC
    RobC at |

    It’s quieter and cheaper than the Noctua A4x20 FLX but note that the flow rate at 7.35 m^3/hr is lower too (vs 9.4 m^3/hr) so the switch will run warmer. Do monitor the temperature to make sure you’re not getting too hot.

  33. Manfred Hofer
    Manfred Hofer at |

    @Lex_France Do you have the FAN failure message in the Webinterface?

  34. Lex_France
    Lex_France at |

    Hello Manfred, in 24h the hight temp was 38°C (100°F). In CLI Show system fan status OK…(too web UI)
    I look at spec of original fan (afb0412vhb) and at 12VCC we are 21m3/h with a4x20FLX max airflow is 9,4m3/h. With AABCOOLING we are 12,9m3/h (with no nose).
    I’ll make a high traffic test with big PoE demand to test the cooling capacity next week.
    I report you the result.
    Many thanks to all.
    Have a nice Halloween.

  35. Lex_France
    Lex_France at |

    This Weekend I made thermal test and the higher was 40°C (on PSU) with very high load:
    – SG500-52P
    – 34 PoE 9W Mini
    – Transfert 5 Po on 2 LAG (2 X 2 SFP10G+)

    For me everything is good.
    Everything is monitored by ZABBIX and performance is very good.

    If somebody wants more detail about this upgrade let me know it will be a pleasure…


  36. Bernd.FFM
    Bernd.FFM at |

    Hi RobC,

    is it possible to get a fully populated with components PCB from you?

    Thanks in advance

    Best Regards


  37. RobC
    RobC at |


    Yes I have many boards on hand and enough parts to build at least 10. Email me at [email protected]

  38. Karim Mneimneh
    Karim Mneimneh at |

    OK So what now ? I’ve been watching this thread since 10 months and I’m hesitating. I have an SG-300-28MP and it’s the noisiest in my rack.

    I don’t get it. How come some much mixed feedback? Is there a solution for the false alarm by rewiring ?

    Also is it the NF-A4x10 FLX or NF-A4x20 FLX ?

  39. Noise boy
    Noise boy at |

    I used 2 NF-A4x20 FLX (3 pin, 12V) in a SG300 -28PP.. Size wise, they are direct replacements for the OEM Delta EFB0412MD but the pin out is different. Just copy the colours on the wires going into the molex, the pins on the molex connector can be removed and repositioned. I used them with low noise cable adapters that came with the fans. They are MUCH quieter than the stock fans but still just audible. The fan status shows as FAIL.

  40. Dirk
    Dirk at |

    Hi noise boy, check out my post of 2016-02-25 at 06:51

  41. Atomic
    Atomic at |

    Note: The SG300-52P model does NOT have Delta fans, but Sunon EB40201SX-D010-C99. The screw holes are bigger than the ones for the Delta fans.

  42. dr_pfiend
    dr_pfiend at |

    Has anyone made progress in replacing the fans of a Cisco SG350-28P?
    I tried with two Noctua A4-20FLX, switched the cables the correct way. The fan starts spinning but stops right away. Tried without the tacho cable, but then the fan does nothing at all. Both fans work well at another 12V source. The Noise of these Delta Fans is really enoying, I would apprechiate any help.

    1. moballa
      moballa at |

      Exact same result for me. At powerup, my A4-20FLX fans spin a couple of RPM and then stop and log fan failure. Did you find a solution?

  43. drpfiend
    drpfiend at |

    Hi! Is there any progress in replacing the fans from a cisco SG350-28P? I have two noctua A4x20 FLX 12V with connectors switched to fit the molex connectors on the board. Both fans start spinning to maybe half speed, then stop completely. Without the tacho connected or ground /12V switched the fans do not start at all. The noise of the original fanes drives me crazy and i would apprechiate any help.

  44. Scott MS
    Scott MS at |

    I followed this thread over two years ago and installed Sunon KDE1204PKV3.MS.AR.GN fans in a SG350-28P that just came on the market. They have now started making noise as they are old and going to not only buy two more of this same fan, but two of the Noctua A4-x20 FLX 12V as well and see how they work.

    1. drpfiend
      drpfiend at |

      Keep us updated, as I tried the exact same thing. I was not able to make it work properly as the noctua fans only start spinning for half a second and then stop. Even with shortening ground and tacho i was not able to get a solution.

  45. Simon
    Simon at |

    Firstly, thanks for this article and all the comments. I have an old Cisco SG300-28MP and I wanted to quieten the fans for residential use.

    Silly me, I bought fans before reading *all* of the comments! As people have pointed out, the Noctua A4-x20 FLX 12V are good but in these switches they start for about 1-2 sec then switch off. A check of the pins indicates the voltage is dropping to ~5-6 V which doesn’t seem to be enough to drive the Noctua, given they run at 1/2 the RPM of the stock fans. (I’m sure if the switch got hot and the V ramped up they’d kick in… But I’m unable to test that properly so decided against relying on an assumption!)

    Checking the wires of the ‘jumper cable’ between the power supply board and the main circuit board indicated that the reds and blacks were the standard +12V lines; used multimeter. So I cut one pair of these and connected in the little ‘sockets with wires’ that Noctua give you in the box. So I had 4 little sockets hanging direct off the +12V and the fans plug into these.
    Note the 20mm fans fit neatly but *just* between the case and PSU in my switch. I would not recommend this solution for any production environments where load will be high. I’ll have max 10 devices (wifi APs, IP cams) drawing low load so I’m happy this will not heat up significantly.

    I’ve then added the ‘ultra low noise’ cables to bring the 5000rpm of the Noctua down to ~3300rpm and pretty much silent. Airflow is subjectively 1/3 of the stock coolers in this config; with the 5000rpm it seemed about 2/3 of stock.

    Some readings:
    ‘Decibel X’ app on iphone SE held 15cm away. Idle load – no ports connected.
    Stock fans ~60-65 dB and drawing 29.5W by plug in power meter,
    With 4x Noctua ~44 dB, power meter is 24.0W (this was on ‘ultra low noise’ cables)
    (Note 44dB is only showing as 2dB higher than my quiet office with zero equipment in it other than me and my laptop.)
    Don’t take readings as perfect – software on a phone and a plug in meter aren’t my idea of precision monitoring.

    Subjectively the noise is a frankly a quarter of what it was.

    Thanks all who have posted – you have helped. I have photos of the inside of the switch but no way of posting them here. (Mod/admin, email if you want those photos – happy to share.)

  46. Nyausoft
    Nyausoft at |

    I have a new Cisco SG350-28P and I also wanted to do something with the fans. I also tried to change them to a Noctua A4-x20 FLX 12V but have the same issue, the fan stop after 1-2 second. I would not like to connect somewhere else (manualy), and I realized that the main problem is not the fan. The problem is the vibration, the whole switch case is vibrating and therefore heard it so loud. If I put up the fans and start them in my hand they are not too noisy. I did the following:
    I put it around with self-adhesive felt and island trip and mount them with anti vibration mounts.

  47. moballa
    moballa at |

    Ok – In my attempt to quiet down my Cisco SG250-26P 26-Port Gigabit PoE Smart Switch, I went a bit crazy and bought 3 sets of fans from 3 different manufacturers. The stock fans used in my switch are from Delta Electronics model AFB0412VHB.

    Here’s the lineup of possible replacements:

    – Noctua A4-X20 FLX 12V (40x40x20)
    – Sunon MF40201V3-1000U-G99 (40x40x20)
    – Delta Electronics AFB0412LB-F00 (40x40x15)

    Pictures here:


    Results on workbench:

    – Each fan when connected to my power supply would start spinning at less than 5 volts.
    – The Noctua was the most quiet at 12V (using only my iPhone as a meter) followed by the Delta and then the Sunon. However, not a huge difference between the 3 but each was a huge difference from the stock fan.
    – The Noctua (subjectively) pushed the least air, followed by the Sunon and then the Delta. However, each pushed much less air than the stock fan.
    – The Noctua had the least vibration followed by the Delta and then the Sunon. The stock fan had much more vibration than all 3 likely because of the higher RPM of the stock fan.
    – At startup of the switch, the fan ports + and – leads show about 6.5 volts.

    Results when plugged into Cisco switch:

    – Noctua would spin up for a second and stop – This is consistent with what many others have posted on this thread. Cisco logs show Fan 1 and Fan 2 as not operational. Fast blinking orange light on front panel.
    – Sunon would not spin at all. Cisco logs show Fan 1 and Fan 2 as not operational. Fast blinking orange light on front panel.
    – Not sure why the Noctua and Sunon don’t spin as the switch is pushing 6.5v on startup which was more than enough to get the fans to spin on my workbench power supply.
    – The Delta spins fine. Cisco logs show Fan 1 and Fan 2 as operational. Green solid light on front panel. Almost silent operation. All good.
    – Before mounting the Delta fan, I used the Noctua brown rubber dampening gaskets around the screw holes and placed a bit of foam tape under the fans to isolate any vibration. Not sure if this helped as I didn’t test sound levels before this measure.
    – After 3 minutes from cold start using the new Delta fan, the log shows “FAN’S speed level – 0 changed to level – 1”. This is consistent with the stock fan.
    – After an hour from cold start using the new Delta fan, the log shows “FAN’S speed level – 1 changed to level – 2”. When using the stock fan, it never called for speed level 2. At speed level 2 with the new Delta fan, no difference in sound level from speed level 1. Still very quiet.
    – After 1 week of operation, no fan related errors reported. Speed level remains at 2. All operational and quiet.


    My SG250-26P Cisco switch became very noticeably quiet by swapping out the stock Delta Fans with the Delta Electronics AFB0412LB-F00. No need to jumper the tach line to gnd as suggested by others on this thread to bypass the fan operational status logic. All works as expected and quiet.




    1. Mark
      Mark at |

      Marco – I bought some of these from Amazon and they would not spin up? The part numbers are the same. Any thoughts as to why?

      1. Mark
        Mark at |

        I should note that I put them into an SG300-28P which I think it very similar to your switch

      2. moballa
        moballa at |

        Was the stock fan in your switch Delta AFB0412VHB?

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