[Fnoord]

> I have ten gigabits throughout most of my house, and you're right: copper is not happy pushing ten gigs.

DACs are copper, and they're happy.

> I have another Thunderbolt dongle that has an SFP+ module, so I ran a fiber line from my switch to my computer, and that runs considerably cooler. That's what I use nowadays.

This is also what I am doing, and I love it. Much better and more reliable than WLAN. I want as much wired as possible.

However... recently, Realtek released several products adding cheap, affordable, low-power 10 gbit SFP+ and PCIe copper (even certain for routers/switches, too). STH did reviews: they're performing. Specific chipset are: RTL8127, RTL8127AP (servers, with management), RTL8127ATF (fiber, no 10/100 mbit)), RTL8127AT (idem, but copper), RTL8159 (USB-C), RTL8261C (SFP+ copper, and media converter). See the examples here: [1]. I've already seen various been selling since ~December on AliExpress, especially copper RTL8127 variants (back then, even one RTL 10 gbit PCIe SFP+ variant). There appears to be one caveat: macOS isn't supported, Windows and Linux are.

I get the case for PoE, but PoE is apparently not as power-friendly as using a dedicated charger. I do find it much more elegant though.

Edit: I'd like to add that I've been having good success with Aquantia AQC100S which I use in my desktop (running Linux, and using a SFP+ for 10 gbit fiber), as well as a Sonnet TB3 (to SFP+ for 10 gbit fiber, running macOS M1 MBP). Both don't get hot, don't use a lot of power, and the connections saturate. Mind you, it is important to specifically go for the AQC100S and not the AQC107 or AQC113 which are both much more common. Both use more power. Because I got good success with these, and my router is sporting a X710 4 port SFP+ NIC (which could be more efficient, to be fair, but it is what it is) I am no longer interested myself in any alternatives. I'm settled.

[1] https://www.techpowerup.com/337113/realtek-to-bring-affordab...

[ploek]

> DACs are copper, and they're happy.

Yeah, but DACs are pretty short and tend to have much thicker cables than regular copper Ethernet.

[jiveturkey]

> DACs are copper, and they're happy.

Well come on. GP really means category cable (twisted pair copper) is not happy at 10Gb distribution lengths (so-called horizontal cabling, although in a home it may span multiple floors without IDFs). That's kind of obvious context.

DACs are not category cable; they are twinax, short, and bulky.

[Fnoord]

Still, it is useful to mention.

If PoE required: use copper twisted pair.

If both sides SFP+ (preferred, but not always possible):

Physical presence: DAC (very cheap).

Not physical presence (e.g. has to go through wall, floor, or longer distance): fiber (OM3 are very cheap but apparently the color being translucent is regarded as nice).

Else: copper twisted pair.

I've applied this on my (rental) house. One server has a 10 gbit copper twisted pair NIC because it also has a PCIe switch with M.2 storage on the same physical PCIe board. Two WLAN APs are powered by switch in fusebox. The Unifi Protect appliance is also powered by twisted pair copper. But I was also able to get an OM3 fiber through the same wall hole.

And always terminate at walls. So if a cable in house goes bad, the one through the wall or the socket is unaffected. Works with both fiber and twisted pair copper.

You can already notice it in this post. DAC barely is part of the content. It is fire and forget, no caveats, lowest latency and lowest power usage. So it tends to be forgotten, but a DAC cable is useful if both devices got physical (vicinity) presence. An alternative could be networking over TB.