SX6012 3D Printable Top for 120mm Fans

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cy384

New Member
Aug 19, 2022
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Even with the minimum fan speed hacks, I found my SX6012 to be pretty noisy, so I've designed these 3D printable parts to replace the top cover, allowing 120mm fans. With a cheap fan controller, I can set the speeds low enough to be quieter than my PC.

all.jpg
I've put the files on github along with some notes. Basically, just print one of each part (roughly 12 hours of printing on my prusa i3). The three top pieces do require supports under the tabs (print each flat side down). I'm using this fan controller but anything should work.

Caveats:
* It's taller than 1U now, but otherwise the dimensions are the same, so it should still fit if you have rails etc.
* You will have to solder a little bit to power your fan controller
* Be careful of the PSUs when you open the case!
* Due to the pretty optimized airflow of the original setup, my design makes the flow somewhat worse. The goal is that the front fan blows at the CPU heatsink and top of the main PCB, the rear fan blows over the PSUs and under the main PCB (where the switch heatsink is).
* There's less airflow directly out the front, so cooling may be more of a problem if you have any really hot transceivers
* Put guards over the fans if you're tempted to poke the blades!
* It will complain about fan speeds, hope you don't mind a red status LED

Anyway, it's been running nicely for a few weeks. Hope this saves some ears/sanity!
 
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Stephan

Well-Known Member
Apr 21, 2017
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Awesome awesome awesome!!

Any particular reason for the holes on the forward plate? Shouldn't these be closed so more air is pushed out of the front?

Improvement idea: Cover non-fan-area with copper sheets, "collar'ed-up" the fan sides, connected to metal of chassis and also to fan guards, to limit EMI.
 

Bjorn Smith

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Sep 3, 2019
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Cool,

So temps are running @ what?

How does the switch cope with 0 fans active? There must be alarms all over the place?

I replaced my fans with different delta fans - noise are a little less than original fans with the "fae command" applied - and temps are the same - but it would be nice to get rid of the noise entirely. My highest temp is the cpu2 running @ 70 degrees, which is hot but within the OK range.

I am also thinking that 3d printing a shroud of some sort for the innards, so directing the airflow to where its needed could improve temps.

Also - an alternative solution is to just not use a fan controller - hook up e.g. low noise noctua's directly to the switch (with correct pin out assured obviously) - and then just run the fans at full tilt - which will probably still be less noisy - but might generate enough air to cool it down better.

Any particular reason for the holes on the forward plate?
My guess is that the fans do not have enough static pressure to push through the QSFP+ cages - thats the nice thing about the 25mm screamers - a lot of static pressure.
 

gb00s

Well-Known Member
Jul 25, 2018
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Nice!

Did you also consider changing the original DELTA fans into Noctua's 3pin and just add the front fan and position it a little bit more to the front where your holes on the forward plate are? This way you shall have a much better air flow as original attended? The original is also not very optimized as you need a lot of pressure (therefore the original fans) to get air moving from back to front. With the 40mm Noctuas you get just enough constant air moving in, but slow. Thats good. With a 120mm fan pulling from the forward plate, you accelerate air flow out through components, which is always better. Its known that keeping underpressure in a case is much better than excessive pressure. Your setup is building a lot of excessive pressure. Nice side effect shall be than you suck also heat from the port cages.

@Freebsd1976 also posted one day >> https://forums.servethehome.com/ind...-as-mellanox-sx6xxx-on-ebay.10786/post-330093 about a bigger and custom made heatsink. Was never able to find a post about it.

EDIT: Added comment + typos
 

cy384

New Member
Aug 19, 2022
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cy384.com
My guess is that the fans do not have enough static pressure to push through the QSFP+ cages - thats the nice thing about the 25mm screamers - a lot of static pressure.
correct, these fans don't have a ton of pressure, especially at low speeds

Did you also consider changing the original DELTA fans into Noctua's 3pin and just add the front fan and position it a little bit more to the front where your holes on the forward plate are?
I did, but for noise reasons I really wanted to do only 120mm fans. It's definitely not perfect, but I think it's good enough, and I got tired of messing with the design!

Is the backside where the fans were open?
there's a part to cover the rear holes

here's a crude diagram of the switch and my parts: side view cutaway, blue is 3d printed parts

1676210895582.png

here's my temps (again, with the fans set at very low speed, so they could be cooler if I cranked them up)
 

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