Hi all,

I have been having mixed results with a few CSS326-24G-2S+ running SwOS 2.1 and 2.2. After 10 to 12 days, they would stop forwarding traffic and all connected devices would stop showing an active connection.

Seeing as the switch shows 60-61 °C temperature running idle I was wondering if it would help with stability if I added active cooling.
The cut out for a 40mm fan is already there, as is an accessible 24V rail (J2) next to the power connector (J1).

The plan was to install a EBM Papst 414 or 414F (1W power req.), add a shroud, and have it blow air on the chips.

What do you folks think? Worth the effort?

I am interested in your modification, my CSS326 is usually running about 69-70c.
Please let me know your results.

Alright, time for results.

First of all: The 40mm fan cutout in the back is loud as hell. If you want to avoid noise you'll have to either remove the cutout as a whole or place the fan further inside the case.
I ended up placing the fan, indeed an ebmpapst 414, next to the system board. If you look a the bottom of the case you'll see a hole that you can use as a start for the fixings. That way, combined with a little shroud, the fan is blowing directly onto the little black heat sink and further down the big aluminium one.

As powersource I ended up using the empty J2 connector. Biggest downside: No power if the switch is running on pure PoE power, i.e. no PSU connected to J1 connector.
In my case it's good enough, as I only use the PoE input as backup supply.
I did add a 330 Ohm resistor, to reduce fan speed and power draw. That way it's quiet enough to use in the open in the office without users complaining about the noise.

Right now, the switch has been stressed for 3 days with a constant 21-22 Gbit load and I have yet to see the temperature sensor report more than 43°C, at an ambient temperature of 23-24°C. Idle is around 36-38°C.

All in all I'm content with the mod.

The reason could be elsewhere. The CSS326 is tested for up to 65C AMBIENT temperature. The temperature reported by the sensor can easily be above that and have no effects. How about the SFP modules, maybe they have lower supported temperature? What is the ambient temperature in your room?

The reason could be elsewhere. The CSS326 is tested for up to 65C AMBIENT temperature. The temperature reported by the sensor can easily be above that and have no effects. How about the SFP modules, maybe they have lower supported temperature? What is the ambient temperature in your room?

Ambient room temperature was 22-23°C, in the 19" rack it get's up to 28-29°C. Highest i ever measured inside the rack via network thermometer probe was 31°C.

SFP modules in use are Finisar FTLX8571D3BCL, which should be good up to 70°C. Right now both are running at 35 and 36°C.

In the end, my issues of instability might have come from the old firmware. Deployed both the fan mod and the upgrade to version 2.3 at the same time, so I'll never know.

I have a CSS326 (SwOS 2.10) running currently at 85C (!!). I only noticed because my RJ45 SFP+ module started to drop packets and when I went to remove the module it was frikkin' red hot. I moved the Cat6 cable to a spare 1Gb/s port which brought back connectivity but HOLY COW - 85C on the mainboard and a red hot SFP module??

This is home use and is located in a 19" network rack on the wall in my garage. It's hot here today - 33C but all my other network gear is fine including the RB3011 router which is located just below the CSS326. The RB3011 is running at 45C which is of course perfectly fine.

If I blow air into the back of the CSS326 using an air wand on an air compressor the temperatures drop down to the mid 60s.

I'm guessing I'm going to need to stick a heat sink on top of the SFP cage inside the case, and add some active cooling?

Did you read S+RJ10 general guidance?
https://wiki.mikrotik.com/wiki/S%2BRJ10 ... l_guidance

Did you read S+RJ10 general guidance?

No, as this is a Ubiquiti branded SFP+ module (it was cheaper here in Australia than the Mikrotik unit). However the same problem described for the Mikrotik model as per the general guidance page applies. The product page for the S+RJ10 module now also says it's only suitable where there's active cooling in use.

I will be adding a cooling fan to my CSS326 and sticking heat sinks to the accessible parts of the module itself as well as one to the SFP+ cage inside the case. I have some of the correct style of heatsinks available.

Holy CARP! I just fitted a 2 watt 40mm 24V fan to the back of my CSS326 and the reported temperatures dropped from 70C down to 38C!
Those are *stellar* results. I've already fitted heat sinks to my SFP+ module, so let's see if the additional air flowing over the SFP cage (practically opposite the fan) helps as well.

The fans I chose are NMB 12608KL-05W-B39 units and are very quiet even pushing air through the fan cutout in the case. I was concerned that I would perhaps need to check and re-apply the thermal compound to the heatsinks on the chips, but with these results I'll be skipping that and also not bothering with attaching heatsinks to the SFP cage.

It's been a few weeks and my switch has maintained low temperatures under 50C in all circumstances. I have permanently fitted the fan to the switch and also ducted the air so that it blows towards the SFP cage. I did not need to remove and re-seat any heatsinks or change thermal paste/glue to achieve these results.

I consider this a permanent solution to managing heat in the CSS326 chassis.

My experience with CRS326-24G-2S running RouterOS - I buy first unit 6 months ago and start using it actively from the first date. The temperature reported in System Health was always above 70 degrees. Most of the time between 73 and 76 degrees. I use the switch ONLY for L2 so the CPU don't handle any traffic. Yesterday I buy second unit and this time decide to put fan inside. After the modification, today I swap the old unit with the new one. Now reported temperature in System Health is 48-52 degrees and the temperature of SFP optical module is 40-42 degrees. Inside the rack the temperature is 26 degrees. I think this is perfectly fine, so I will modify and the old unit before put it in production next week.

What I did:
- buy 40mm ball bearing 24V DC fan Evercool EC4020H24BA
- use J2 connector on the board to feed with power the fan
- also solder one 120 ohm resistor on the "+" wire to lower a little bit the voltage, the fan is running on 20V now

I don't know why the CPU is running so hot even when there isn't any L3 traffic on the switch, maybe the heat sink is very small for passive cooling.

Holy CARP! I just fitted a 2 watt 40mm 24V fan to the back of my CSS326 and the reported temperatures dropped from 70C down to 38C!
Those are *stellar* results. I've already fitted heat sinks to my SFP+ module, so let's see if the additional air flowing over the SFP cage (practically opposite the fan) helps as well.

The fans I chose are NMB 12608KL-05W-B39 units and are very quiet even pushing air through the fan cutout in the case. I was concerned that I would perhaps need to check and re-apply the thermal compound to the heatsinks on the chips, but with these results I'll be skipping that and also not bothering with attaching heatsinks to the SFP cage.

Hi Kaldek. I am looking at doing the same, with board at 70 constantly and SFP modules at 87! I don't like having equipment running at these temperatures and they will only rise further with the summer temperatures later on.
Can you help a little with the procedure? Does the fan you mention come with the correct connector to just plug into the board? Which connector is it on the board? Also, how did you attach heatsinks to the SFP modules exactly. Any help on the procedures would by very much appreciated.

After reading this thread and found Eric Shewe (https://www.pickysysadmin.ca/2022/08/1 ... tallation/) post, I start hunting fans for my CRS and CSS. Here my results:


CSS326 45-47°C

CRS326 49-50°C

The 24V fan is rare but I choose not to use 12V version because there will be more works to do. And I'm lucky to get four 24V DC fans with 3 wires.

Here my list:
1. 24V DC fan 40mm x 40mm x 10mm
2. Screw Metal M3 - 12mm (my fan 10mm)
3. Nylon M3 Pilar Spacer PCB
4. Extra cable and cable's fan connector

This will cost around $2 USD
And the temperature drops about 20°C, from 70 to 50.

You only need 2 wires for DC: black (-) and red (+). Maybe you get different color combination, and its depend on your country.

Computer fans has 2, 3 or 4 wires (mostly 12V). The first 2 for electricity, the 3th for sensor and fans speed, the 4th for other control like LED. So, no matter how many wires its has, we only need the black one (-) and the red one (+).

Mine has 3 wires: black, red, and yellow. And I only use black and red.

Behind the big heatsink there is a header that says FAN in and has three holes. Cant that be utilized?

Hello
I followed your advice and installed a 24V 40mm fan in the back , blowing air outside the case for my CRS326.
The issue is that I put 2x S+RJ10 and their temperature went to 87 C and a blue line in the logs...
the internal temperature was to 50+
the ambient temperature was 16 °C.

what can I do to have 2x S+RJ10 on the CRS326?

You might have heating issues when using two S+RJ10 next to each other. They should not be placed like that.
There must be one empty between them. Or place one on each group of ports.

Please read more about this in the S+RJ10 documentation.

I have read the docs, but on a CRS326 I havent any other way to use them!

Ah, i really dont know then :)

Is this mainly when using SFP ? Or do you also encounter these temperatures without ?

The real issue is when using 2x S+RJ10 that is my user case.
We installed 4 fans 40x40x10
one in the back
two blowing on the sfp+ glued on the case
one aspiring air upside (we made some holes on the case).
when it is possibile I will send the pic

the temperature went from 87C (sfp+) to 61 and the ambient from 59 to 30

A few pics would be nice.
How did you provide power to those fans ?
I have a CSS326 on the way and I’ll not be using the SFP+ directly but if I can already make the needed adjustments would be nice.

We connected them to an external 12V power supply.
These are pics during work in progress.
I connected together the two s+rj10 to have them on and heating