Guide - Replacing the NetApp DS4243 / DS4246 PSU Fans


Whats up everyone!? Your resident Gohan here! :smiley:

This guide will help you all in replacing the fans in your Stock NetApp Power Supplies!

Ultimately the goal is silent operation while maintaining most the cooling performance.

Now, there is really only one major risk involved with doing this.
Shocking the F&*^ out of yourself. (This can happen if your not careful. Just be aware of what you are doing and don’t stray from the guide, capacitors can hold a charge for a very long time). :zap:

Other than that. Have fun with this. :sunglasses:

Parts you will need :hammer_and_wrench:

  • Heat Shrink Tubing

  • Wire Cutters/strippers (nothing too heavy, these wires are pretty thin)

  • Philips head screwdriver (anything meant for PCs, like the amazing iFixit kits or amazon $9 ones)

  • 2x 80mm fan with 3 wire

  • Something to combine the 2x fans together. (noctua fans come with rubber inserts which i repurposed for this as well)

(I used Noctua NF-A8 FLX Premium 80mm Fans)

You will need 2x Fans PER Power Supply Unit

Lets Get Started

First things first. Power off your net app, and pull out the power supplies.
(I highly recommend you mod 2x of them, and run them together so that the cooling capacity is even)

There are 14x screws on the body that will need to be removed. Save this screws as you will need them later.

Next. Once you remove the screws, you will need to pull apart the PSU case. (It may take you a moment to get it off. Just be gentle with it as you take it off. It folds off of one side to facilitate easy assembly.

After you get the PSU case disassembled you can finally get to the internals of the PSU.

As you can see, there are 2x 80mm thicc fans inside of it.

These fans are 80mm delta fans and can move some serious air (and they are loud as well).

The wires you see running off from the left and going to the right are what controls the fans.

You will need to undo the fans from the PSU chassis by unscrewing the 4x screws and nuts that hold the fans into place. Once the nuts are off, you can slide out the screw-bolts from the rear of the PSU.
(I recommend you keep these for later, just in case you want to use “thicc” fans like what are currently in use)

What Next?

Now that the fans are loose. You will need to snip the zip tie closest to the fan. (This will allow you to easier access to the wires)

As you can see, you have 2x fans, which means 2x sets of wires to contend with. (I personally kept both sets of wires separated from each other so that they would not get mixed up)

The reason being that the NetApp actually sees these fans individually, so you do not want Red#1 and Black #2 mixed with speed sensor #2 (this could cause major problems later on since it would try to ramp power to fan #2 and cause a mismatch due to different red and black pairs mixed together)

Start with gently cutting off the wire sleeve (the long black plastic thing).

Once that is off, you should be able to pull the fan closest to the yellow covered coil out of the PSU chassis.

Cut the wires that are connected to the fan. Now take your new fan, and cut off the 3-pin connector.

You will want to make sure you have enough wiring slack. (If you are not good at this, make sure you leave yourself enough wire to play with on both ends, we can always tidy up extra wire-length later with zip-ties)

Strip the ends of your wires,
twist them,
slide on the heat-shrink tubing,
then combine the wires using the method you prefer.
(I used this method here for a perfect inline wire splice, no solder needed)
After they are spliced together, heat up the heat-shrink tubing and make it nice and tight)

Your wires should look like this. (If you are using Noctua Fans, other fans YMMV)

Wiring Diagram

Rinse and Repeat for the 2nd fan.
Once both fans are wired up, you will now need to take off one side of the rubber edges on each fan)

Now that those are removed, you will combine the fans together, as you can see above, I used the rubber fan inserts to combine the fans.
(inverting 2x of the 4x in opposite sides) (Since the rubber inserts are not meant for such tight spacing, i had to cut the edges of the head off so that it would fit)

Leaving the other rubber edges help reduce vibration against the metal PSU chassis, which can also potentially reduce noise.

Now that you have the fan “cluster” built. Its time to insert it into the chassis.
This is a delicate procedure and it will require you to gently lift up the metal tabs so you can squeeze the fan into the space.

Almost Done! :smile:

Now it is time to screw the main rear fan to the chassis.
You will need the 4x regular case fan screws and a Philips head screwdriver that fits them.

As shown above, you will screw these in so that they are tight. If you notice the rubber edge squishing out of the fan holes, this shows its perfectly tight.

Next step is to tidy up any loose wiring inside the power supply. This is YMMV.

The goal is to have wiring that looks close to this. (As close to factory as you can get in my opinion)

Once you are done with wire cleanup duty. Just put the PSU chassis back together and you will be good to go.

(Once Again, please use 2x-4x PSUs for ample air-flow, you do not want to starve the Net-App of Air.
Its bad for the NetApp IOM modules, and the Drives that are installed.)

THATS IT! :smiley:

Finally, here is a video of the silent PSU.
(AUDIO ON) :ear:

Post Completed on May 13th, 2020

1 Like

How did you go? I tried one out of the 4 with some generic fans but now all the other fans run at full speed.

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I replaced all the fans and the netapp is absolutely silent. Let me finish writing up the guide. (the netapp is technically running the fans at max speed, but that doesn’t matter since they are all the same type and speed)

Its definitely worth doing and silent operation is amazing. (you definitely sacrifice airflow, so make sure your ambient room temp is not too hot or you will increase the internal temps)


Hey there, great write up. I have a few questions:

  • Do you happen to have the model number of the stock Delta fans? I’m curious about the specs.
  • Also, what’s your opinion on the modification now that it’s been some time?
  • How are your temps?
  • Did you complete this to the other PSUs?
  • The PWM version NF-A8 has a little more oomph compared to the FLX. Since you can run a 4pin PWM fan off a 3pin connector, do you see any issue with running the PWM version?

Thanks for your efforts and time!


Hey @TomTom !

The Delta PFB0812DHE DC Brushless 12V 3.30A fans were the original NetApp PSU Fans.
Here is a link to a PDF of the specs

These fans pull quite a bit of wattage and after replacing these fans, the Overall Power Consumption of the NetApps reduced quite a bit.

Currently I am only running 1x NetApp with 2x Modified Power Supplies ( 4x Fans in total)
The modification that I made is excellent, and I have had zero issues with it. Most of the cooling is dependent on the ambient air temperature of the room, and I have seen temps as high as 55c, and as low as 41c, which is not really terrible all things considered (all 24 bays are populated) (this is the temperature of the netapp sensors, not the drive temps themselves, they usually stay around 42c)

I specifically chose the NF-A8 FLX fan model. The reason being is the NetApp itself modulates the fan speed by increasing or decreasing voltage. The 3-PIN FLX fan is Positive, Negative, and the Speed Sensor. I personally would not run a PWM fan on a voltage controlled system, since the motor stepping is meant to be controlled via PWM.

No problem at all, and feel free to join the Sudo.Fail Discord


Hi Gohan!
thanks for the replacement guide!
I replaced the fans on two PSUs with the Noctua NF-A8 FLX.

But after a while the fans run at a very high speed, so I’m worried that they might break. And even much louder than the originals.

Do you `ve an idea what here is the problem / solution?

Thanks and greets!

1 Like

Hey There! Welcome!

The NF-A8 FLX Noctua Fans are 2000 RPM (+/-10%) fans, so they physically can not be louder than the original 9000 RPM Delta PFB0812DHE fans. Even at max speed.

Noctua acoustic level is (16.1 dbA @ max RPM)
Delta acoustic level is (65 dbA average , 70 dbA @ max RPM)

There are a few questions I have for you.

What is the ambient temperature of the room where the NetApp is located? C or F is fine. :smiley:
How many drives do you have installed?
How many PSUs are you using per disk shelf?

As for that last question.
You can not mix modded and unmodded PSUs in the same DiskShelf unit.

This is due to the NetApp speed profiles which sets the the modded PSU to “MAX SPEED”, and it causes the other non modded units to run at MAX SPEED as well.

^I feel like this might be the issue your facing. Since the Stock fans tend to run around 4K RPM normally vs 9K RPM if there is a mix of modded/unmodded PSUs.

If running only 2x modded PSUs, I recommend you run them at opposite ends from each other to distribute the airflow more evenly.
(If the DiskShelf unit came with 4x PSUs, then you might need to either mod the other 2x “Stock” PSUs, or get 2x PSU blank inserts. This is due to the airflow channels inside the netapp, and having open PSU slots cause loss in static pressure which degrades cooling performance)


When you say that power consumption has been reduced quite a bit by swapping out the delta fans, do you know specifically how much? I.e. has it gone down 40 watts etc. I only ask because I have one of these units myself and I’ve been toying with the idea of swapping in some Noctuas myself. Mine currently idles at 175-ish with 9 sata drives, and I’d love to bring that number down


Each Delta fan pulls 33w max @ 9000 RPM.
Granted, depending on the ambient temperature will depend on if they’re running at full speed or not. Either way, each fan is pulling roughly 15-33w…

There are 2x fans per NetApp PSU, so each PSU could pull 66w max.

Replacing the power supply fans with Noctuas made a significant difference in power consumption.

It’s hard to gauge the exact usage currently, but I estimate my NetApp with 22/24 drives is pulling 250w


Ah I see. Still, even going by a rough ballpark it seems worthwhile. Assuming the deltas in mine are running at 60%, that’s like 80w total. Where 4 x Noctuas are like maybe 5w on full blast would be 20w. If/when I eventually do this mod, I have a power usage meter so I can post up the watt usage difference so we can have a rough before and after for anyone else considering doing this mod. Thanks for posting all this!

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I picked up a DS4246 and mine has power supplies with 4 pin PWM deltas in it. I picked up some NF-A8 PWMs and the power supply now trips a DC Fault light and shuts down. Any ideas on what happened and how to fix it?

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Any luck with this? I have a 4pin pwm delta as well.


It is an old topic, hope someone can still help. The coloring of the fan wires in my PSU is a bit different than the one shown in your guide. As you can see from the image, the first three are the same red/blue/black colored wires as in your example. The next 3 are a different color. The wires are also not directly soldered to the board but connected via a connector. Can I assume the order of the wires is the same as the red/black/blue in the guide and use the same logic on my PSU? Or does my PSU has a different setup for the fans?

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Do you mind sharing the model # of the fan inside your Power Supply Unit? As well as the full PSU model and date code?

I appreciate the picture! That definitely helps me get an idea of the layout!


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Thanks for the quick reply and support!

Here the picture of the fan with the different wire colors and one with details of the PSU.



Thank you for posting those pictures. It seems the fan model is the same, but the revision/variant is different. The one you have is the PFB0812DHE -BL1K variant

This fan is a 4-pin PWM version. I do not know the EXACT wiring for it, but I did reach out to Delta to see if they can provide a specification sheet.

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Hey Gohan,

Thanks so much for the guide it worked a charm I have actually just done the same exact mod to my PSUx2 and i had a similar problem freek, I belive it is the 4 pin PWM variant however it’s only wired with 3 pins and also works with non-pwm. the pinout on the motherboard is the same. it works for me fine both fans appear to be spinning.


No Problem at all! I am glad to hear that it worked like a charm. :smile:

1 Like

Thanks for clearing that out! So this means that I can follow this guide and use the Noctua FLX fans?


I did this mod about a month ago but I accidentally bought the PWM noctua fans instead of FLX. After some tinkering with the wiring it seems to work fine but two modded PSU’s is not enough for some hot running disks haha