I had a old Macbook sitting on, but idle, for a few days. I just turned it off, and found the ethernet-to-USB-C dongle was really warm.
Not worryingly hot, but definitely "electronic device doing things"-hot.
Is that normal for such a simple device?
The external harddisk and the Macbook itself were cold to the touch.
@pixelambacht Those things contain more than just some wires. They typically include a controller and some (very small) memory. So not unimaginable they can run hot.
@bramus I guess I just wondered why it acted like it was working really hard, when no data had been sent over the wire for over a day (it was running backups). But I guess that thing needs to be alive all the time, in case data does flow!
@pixelambacht Yeah, there’s still a small but constant amount of traffic happening (e.g. SNMP heartbeats, time syncs, etc.) even when you are not actively transferring data, so it’s constantly on.
Oct 12, 2026, 11:55 AM@pixelambacht i had one on the XPS13 which ran hot. So, maybe the cheap USB-C to ethernet chipset doesn't do power management very well
Oct 12, 2026, 12:02 PM@pixelambacht a theory: i suppose if Wake-on-LAN is going to work, the adapter will need at least some power continuously, even if (and actually, in particular) when the host is "off".
@drj Yeah, I figure that's what's going on!