SFP requires less energy than RJ45, only 0.7W/port. The MikroTik 4-port CRS305-1G-4S+IN draws 10-18W.
Which is also why plugging a large amount of DWDM optics into a datacenter switch is a bad idea. Datacenter switches are _not_ designed with this in mind. You run into risks of both overheating the switch as well as overloading the PSUs. A small number of high-power optics ain't gonna break the switch though.
And: 10Gbase-T SFPs have horrendous power consumption, even worse than DWDM SFPs. At these speeds, the signal over copper is mostly mush, and the PHY contains a none-too-trivial analog & digital signal processor. Which, again, is where limitations for 10Gbase-T SFP usage come from. If at all possible, avoid this shit — there's absolutely no reason to have 10Gbase-T inside a rack, for example. Just use DAC cables or SR optics.
If it was known that vendors would try to push their thermals past what the device cage would support, why not address that better?
The general impression I was given is that thermal loads were one of the primary reasons given for vendor-locking pluggable optics, and that the original SFP spec didn't even address it.
I have two of these at home, they're neat little bits of kit.
They're fanless and therefore silent, which is fine until you realise you want to do 10GbE over existing copper cables with something like Mikrotik's S+RJ10 adapter. Then the temps start to rise...
So, I've decided to go completely to fibre, even if it means opening up the walls of the house. Just bought a job lot of used ConnectX-3 cards off ebay.
Those cards are so good. I got a few after seeing them rated in r/homelab and haven’t looked back. The Synology took one and it was about 1/10th the price the official Synology one was.
Agreed. You can find them on eBay for ~$40 a pop, and they work flawlessly on Linux and Windows. I've made a few purchases from the seller "bitsquad" (ships from Kentucky), and he always seems to have Mellanox/Chelsio in stock.