Well, to no surprise to anyone, I have 2 Proscend P180T modules that were overheating in a passively cooled CRS309-1G-8S+ that isn’t even in air conditioning.
Not wanting to give up, I designed a 3d printed cooling “hat” that uses a 25mm x 6mm 12v fan powered by a plug pack. Combined with a few adhesive heatsinks, the modules have cooled down dramatically.
I seem to recall a few people using these VDSL SFP modules, so I thought I’d post here too with a link to the model on thingiverse. https://www.thingiverse.com/thing:5965753
Would also be interested in what people think of cooling options for some SFP modules, especially if they have devised their own methods. As seen in the images in the thing above, the hat and heatsinks do get in the way of other SFP ports, so maybe a redesign is needed.
Hi, I had up to >90C° SFP+ temperatures in my CRS309-1G-8S+ on different 10G Cu modules. The worst culprits were the MT S+RJ10 modules.
I have mostly replaced them by cheap DAC cables, which produce no noticeable heat. The ones I still need, I have equipped with small heatsinks from 3 sides. Between the heatsink and the SFP, I put some heat conductor pads (this is important as some SFPs have no plain surfaces). Then I just put a small cable tie around it to hold the package together.
Works like a charm even in summer (up to 30C° in the room, no air currents) and most importantly makes no noises at all. Also just a few minutes invested.
In another environment I have just replaced the 10G Cu by multimode fiber. Stays cool enough, I did not need to put any heatsinks on it.
Also the whole setup did not cost more (cheap Chinese components of course) than it would have with 10G Cu and the fiber was easier to run than a Cat6A cable.
There’s also Mikrotik’s general guidance on placing SFP modules which generate lots of heat. The linked guidance is specifically about S+RJ10, but it also applies to any other “hot” SFP modules.
Not sure, if it solves the problem entirely (using active cooling, such as add-on fans, is definitely more radical solution which probably works best in most conditions), but it probably does help.
Hi, thanks, mkx! I always kept myself to the general guidance. So I have always left out one SFP+ slot, between the 10GCu SFPs.
Even then my modules got hot enough to have warning messages about overheating SFPs in the logs.
So I did not wait for the summer to come…
I know with the Proscend VDSL modules (which work really well to be honest) that even with just heatsinks and little airflow, taking them out was literally a hot potato scenario. The fans I used are so tiny, and indeed move so little air I cannot hear any difference in volume. It was actually surprising how little air was needed to cool it with the heatsinks.
I have a Fibrestore 1Gbit RJ45 Module, I assume it gets hot the same as others mentioned in this thread. Maybe I should look at designing a fan solution for one of those! It’s RJ45 connector is alot smaller than the Proscend units though.
My fan idea was definitely a “still hot, need to cool this down” solution, but I was quite surprised just HOW well it works. It’s a shame the Proscend modules do not report their temperature to the switch or I would have numbers. Also wondering if there’s a way to maybe hide a 12V step down board to power the fans inside the switch…
For a more modular solution, you could design a small external cooling housing that houses both the fan and SFP modules, ensuring that airflow is optimized without obstructing other ports. Think of it like a mini split system for your networking gear—separating the heat-generating components from the switch itself while delivering targeted airflow where it’s needed most.
You could mount the modules in an external enclosure with dedicated intake and exhaust paths, maybe even with a small temperature-controlled fan to reduce noise when things aren’t too toasty. This way, you get maximum cooling and keep your CRS309 ports accessible. Bonus points if you 3D print some snap-in trays or guides for easy swapping of modules.
Really cool work on the Thingiverse model, by the way! Always fun to see practical DIY mods that solve a real problem.
