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Comment by PhilipRoman | Hacker News Reader

>N100 based computer draw 9W at idle

That number seems suspicious. Right now my i5-6500T server is idling at <5W and an N100 is supposed to be even more efficient.

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9W at idle for the N100 is similar to what I get with my N100 based PC. Although under windows it's often sitting at 10-12W.

I also see lower power consumption with an 8th Gen intel Core system.

The small cores that the N100 use are size efficient, but not necessarily power efficient. The N100 chip is just not that efficient power-consumption wise.

How would you guys properly measure that? I have my suspicion that my Intel processor also quite not too heavy at idling.

Buy a kill-a-watt wall wart.

At Walmart.

I use an electrical outlet meter. It's roughly €10, the only annoying thing is everything rebooting each time I want to move it.

i wonder if there's a market for pre-made cables with a "loop" in the hot wire, for using clamp ammeters, or a cable where in addition to the choke ferrule, there's another "ferrule" - current transformer - on the hot wire with "test points", where those test points are to a transformer winding around the hot wire. That way you could just put those cables on things you want to know the power consumption of, rather than having to move a kill-a-watt or whatever.

I could make either, but they wouldn't be "certified", as i'd be either replacing plugs or cutting into the wire itself to add a pigtail.

Matthias Wandel measures power that way: https://www.youtube.com/watch?v=P47pjVyPP3w

You may be looking for "AC line splitter".

One example: https://www.harborfreight.com/15-amp-professional-ac-line-sp...

Edit: s/splicer/splitter, damn autocorrect.

Yup. They even typically come with separate 1x and 10x loops.

They're a common pack-in item with low- and high-end clamp meters.

The easy path, as someone suggested, is a kill-a-watt that you just plug it into.

The less intrusive path for some definition of less intrusive is a clamp ammeter if you can expose one of the AC wires (you have to clamp around an individual wire, not both hot and neutral). But then you don't need to unplug the system to measure it.

The third overkill option is to have it plugged into a full-time power monitoring and control device, such as a zigbee home automation plug switch. ;)

This can actually be life threatening if done without proper tools and working fast fuses. So just use a kill-a-watt or any other such tool for safety! NB they're maybe not 100% exact but good enough to give an estimate.

A clamp meter does not expose you to any live uninsulated wires unless you are doing it very wrong.

(Although they also tend to be not very accurate for low current measurements. So this isn't a use case I would recommend them for.)

Clamp meters are completely safe. The only risk is if you DIY your power cable so you can clamp one lead, but that's not necessary if you just buy an AC line splitter plug. And those often come with the hot looped around so you can get a 10x reading for better fidelity at lower current draw.

But these days I just skip the clamp meter and throw Ikea Inspelning zigbee plugs anywhere I want power measurement.

Doing anything can be life threatening. We don't need to assume that people who decide to do a thing are the same as you.

There are $10 Chinese kill-a-watts with color display, and live Bluetooth data recording.

It's fun stating a CPU intensive job and watch the graph spike.

Do you have any names or links? I tried a Temu version a while back and even getting it connected to wifi was hopeless.

I have a regular i5-6500 in an HP 800 G2 SFF. It has 32 GB RAM (2x8+16), two Samsung 840 SSDs and a 4-port i350 network card. It Linux as a KVM host with OpnSense and Home Assistant on top.

According to some watt-meter I got off Amazon it idles at 14W with the 4 interfaces UP but next to no traffic. I consider it idling when the CPU usage as reported by the host is under 5%.

Now the watt-meter isn't some top-of-the-line exotic model, just a random Chinese thingy, but it seems to measure close enough to what I expect some other devices to pull.

I can vouch for the power draw in this type of system. I have a Dell OptiPlex 7070 with i5-9500, 32GB and running Proxmox with a Windows VM and a couple smaller instances. I measure 8w idle from my Kill-a-Watt on the system. I was really surprised at how low it is.

Which form factor? Tower, MT, SFF or Mini?

SFF

Thank you! The Dell SFF can only hold one 3.5 inch HDD right?

Yeah, just one. Here is the service manual: https://www.dell.com/support/manuals/en-us/optiplex-7070-sff...

I got a refurbished unit for $180 last year, using this deal (now expired): https://slickdeals.net/f/17490348-dell-coupon-50-off-refurbi...

> How would you guys properly measure that?

I'm using smart plugs that have an open source firmware called tasmota. I can scrape the values using prometheus and can build dashboards with historical data.

USB-c cables with live PD power display can be chained with PD-to-barrel converters for fixed voltage.

the author has a previous blog post about his monitoring setup:

https://www.jeffgeerling.com/blog/2025/how-i-monitor-and-con...

I can recommend those Third Reality outlets as well, I have about a dozen now and they Just Work with my Zigbee dongle (Sonoff ZBDongle-P) and zigbee2mqtt / Home Assistant setup. I use Home Assistant's Prometheus integration to get the data into VictoriaMetrics, which lets me build Grafana dashboards showing the usage of each plug over time.

how did you get a 6500T to idle so low? Is that CPU power or total system power? I have a T part from the next generation, I don't remember the exact model. It's low but it isn't that low.

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.

From what I've read, some N100 systems don't support the same c-states as other systems and don't idle as low.

Depends on what you have active on he board, especially storage that isn’t pushed to an idle state for some reason.

Can confirm 8-9w idle for my N100 homelab server having 1 NVMe SSD, 1 SATA SSD, 16GB RAM.

I may misremeber the exact number, but it was high enough compared to a RPI

That sounds wrong, efficient intel chips should be very comparable to pi's. Measurements for the futro s740 (j4105 CPU) were [0] around 2-4 W idle when properly configured

[0]: https://github.com/R3NE07/Futro-S740/blob/main/power_consump...

I am reading this right now on my N100 desktop and it's 7W

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