10Gb/s Ethernet: switching to a Broadcom SFP+ module

Back in April, I upgraded my home LAN to 10Gb/s. The in-wall cabling is CAT-6 or similar, so I had to use 10GBASE-T. Now, the router I'm using, and the switch in my study, provide 10Gb/s through SFP+ cages; that meant that they needed 10GBASE-T SFP+ modules in order to connect. That kind of module is known to run hot -- sometimes too hot to actually work. The modules in reggie, the router, appeared to be running OK (see the linked post above for charts), but the one in nigel, the study switch, was a worrying 93C. I tried sticking some mini-heatsinks on it, which seemed to help a bit. But the weather got warmer, and eventually the module overheated. I lost access to the Internet from the study, and checking the metrics showed me this: You can see that it's "flapping": the temperature gets up to a level where the module shuts itself down for its own protection -- about 95C, I think -- and then when it has recovered, it switches on again, the temperature rises, and the process repeats. I…