Is the power consumption (and heat dissipation) a function of bit rate? E.g. would the same 10GBASE-T transceiver consume less power when running at, say, 2.5Gb/s than at 10Gb/s?

Would love to understand this a bit better.

(edit: corrected the units.)

Yes (or at least I've noticed it on mine) but worth noting 99% of 10G RJ45 SFP+ transceivers only support 10G and nothing else. Typically it's only fixed copper interfaces that support negotiating different speeds.

The MikroTik adapters are a bit special in that they are more a 2 port transparent bridge where the inside facing portion of the module always runs at 10g and the outside facing portion auto-negotiates. This allows 10G only switch interfaces to support 10/100/1000/2500/5000/10000 clients. In a MikroTik switch it reports back the negotiated speed and the switch can shape traffic to the appropriate bandwidth instead of letting the adapter do it (which I assume is just policed but could be wrong, never tested). I have a 100G switch which is backwards compatible with 40G and allows breakouts so with a QSA can support SFP+ modules... putting this MikroTik module in I can plug a 10 megabit half duplex device into a 100 gigabit port!

Super interesting re Mikrotik adapters. Those (S+RJ10) are exactly what I run, so very relevant, thank you!

I think it's a mixed bag of cats, the support for 2.5/5/10G - somebody made an useful table for that: https://www.servethehome.com/wp-content/uploads/2020/03/STH-...

The whole article: https://www.servethehome.com/sfp-to-10gbase-t-adapter-module...

Super useful, thanks for taking the time to post it.

Very informative table and article, thank you.

Seems so, e.g. this table: https://www.ioi.com.tw/products/proddetail_mobile.aspx?CatID...

  Power consumption (Full bidirectional traffic, 100m cable):
  10G speed: 6.41W
  5G speed: 4.83 W
  2.5G speed: 3.97W
  1G speed: 2.94W
  100M speed: 2.21W

Also https://en.wikipedia.org/wiki/Energy-Efficient_Ethernet