The processors themselves all seem to be pretty efficient at idle (there's apparently no real reason to get a T processor. It just caps performance). It mostly depends on everything else. The only place I know of to get this kind of info is this thread[0] where people have been building this spreadsheet[1]. Some threads on servethehome.com also report when some pcie cards have broken power management which can destroy idle efficiency.

[0] https://www.hardwareluxx.de/community/threads/die-sparsamste...

[1] https://docs.google.com/spreadsheets/u/0/d/1LHvT2fRp7I6Hf18L...

Total system power (as in, drawn from the outlet)

I didn't do any significant customizations, it runs Alpine Linux. Here is my powertop output:

    Summary: 139.6 wakeups/second,  0.0 GPU ops/seconds, 0.0 VFS ops/sec and 0.9% CPU use
                Usage       Events/s    Category       Description
            100.0%                      Device         Audio codec hwC0D0: Realtek
            480.6 µs/s      38.3        Timer          tick_nohz_handler
            469.0 µs/s      24.6        Timer          hrtimer_wakeup
            330.0 µs/s      23.2        Process        [PID 2121] [irq/132-iwlwifi]
            281.2 µs/s      10.1        Process        [PID 3278] containerd --config /var/run/docker/containerd/containerd.toml
             28.9 µs/s       9.5        kWork          toggle_allocation_gate
             52.4 µs/s       7.5        Timer          inactive_task_timer
            279.3 µs/s       4.6        Process        [PID 3279] containerd --config /var/run/docker/containerd/containerd.toml
            363.9 µs/s       4.5        Process        [PID 3306] containerd --config /var/run/docker/containerd/containerd.toml

The system as a whole spends around 95-97% of time in pc8 state.

Which main board are you using? 5W is very impressive. I'd be surprised if it was even possible to achieve with an ATX board without some serious tuning.

I'm curious to know the details of this as well. 5 watts is absurdly low for an ATX system. I've definitely seen 25 watts before. Assuming you went from a 75% efficient PSU to a 90% efficient one, that'd shave off a few more watts but it won't get you that low.

For perspective, I think the typical NIC consumes several watts of power.

It's a Lenovo 310B motherboard.

Wait, so we're talking about a laptop?

No, it's a mini PC.