10Gb/s Ethernet: using mini-heatsinks with a 10GBASE-T SFP+ module :: Giles' blog
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10Gb/s Ethernet: using mini-heatsinks with a 10GBASE-T SFP+ module
Posted on 18 May 2026
in
TIL,
Gadgets
In my last post I showed the somewhat-scary<br>temperatures I was getting on the MikroTik 10GBASE-T SFP+ module I have plugged<br>into nigel, the 10Gb/s switch I have in my study.<br>As I mentioned then, the plan was to try using some of the mini-heatsinks that<br>people use on Raspberry Pis, to see if that would help.
Here's how it went.
I bought a 40-piece set of heatsinks made by the improbably-named VooGenzek on Amazon for €8,<br>and attached two of them like this -- see the bottom module, with the yellow cable:
That was 24 hours ago, and here's a chart of temperatures from that module showing<br>the 24 hours before and after:
You can see the big drop-off in the middle of the chart; it even overshot a bit<br>(I'm guessing because the heatsinks absorbed a bunch of heat initially when I put them<br>on).
The difference looks more dramatic than it is! See where the Y-axis starts.<br>But given that the weather has been<br>pretty much the same today as it was yesterday, that looks like a 3.5°C improvement.<br>Not great, but not nothing either.
In the copious discussion about the last post on Hacker News,<br>one of the most popular comments -- from xxpor -- was that there are two generations of SFP+ modules<br>for this kind of thing; an older one, using a Marvell chip, and the newer one using<br>one from Broadcom. blunden on the ServeTheHome forums<br>made the same point. They both mentioned that a good indicator of which type a module<br>is using is that the older ones tend to be rated up to 30 metres, while the newer<br>ones are rated up to 100.
This one is a MikroTik S+RJ10,<br>which definitely is one of the older ones -- the specific chip is mentioned in the docs.<br>I'm not sure which chip the Protectli modules in my router reggie are -- they're<br>these modules -- but they say they're<br>rated up to 30 metres, so I guess they're probably the older type too.
Looking into switching those out...