Comment by ericd
15 hours ago
10GbE rj45 (normal ethernet jack) spf modules tend to burn power and get extremely hot, like to the point of burning you if you touch it - the manual for my switch said to leave adjacent ports unoccupied if using one of those. The fiber ones run cool to the touch.
Also, not needing to rerun any cabling if we want to bump up speeds in the future, you just change the laser module on either end. These should be good to >100x current speeds. Not the case with copper.
"10GBASE-T runs hot" is only half true.
The real problem here is that 10GBASE-T is ancient. The spec dates back to 2006! And worst of all: it only saw lukewarm adoption by the datacenter industry, so there hasn't really been a reason for manufacturers to refresh their lineups. This means that SFP+ transceiver you buy in 2026 might be using chips manufactured using a 20-year-old node. No wonder it is running hot!
2.5GBASE-T and 5GBASE-T are essentially using the same technology, but you don't hear anyone complaining about it running hot: hardware for this only recently started to become available due to consumer demand, so any hardware for that is being manufactured using more modern technology, which means a lower power use.
It's still going to consume more power than fiber, but a modern 10GBASE-T SFP+ transceiver should not be burning hot.
Ah, thanks! That helps explain why it seemed like a sort of poorly executed/ill conceived product. Any good brands you know of? I think I just got something random from FS.com or maybe even Amazon.
Realtek recently made a new 10GBASE-T NIC that consumes much less power:
https://www.servethehome.com/cheap-10gbe-realtek-rtl8127-nic...
Fiber runs cool because it's operating well within the physical capacity of the channel. Copper needs an incredibly high signal to noise ratio to overcome the limitations of its medium. Copper will consume 5-10x more power than fiber for the same # of bits transmitted.