Network cable or WIFI?

Crivens

Crivens

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We were having this discussion wether to use WIFI on laptops or a network cable, arguing from a power consumption viewpoint.
What $SEARCH_ENGINE can tell is, well, diverging. So suppose you have one WIFI router, does it save power when you switch off the WIFI and run a cable there, or is the power consumption of the LAN hardware higher than the WIFI module+router?

Maybe one of you has measurements, inquiering minds want to know...
 
I think a wireless router don't use that much power in order to matter in a household. If you are concerned about the savings how about don't use the second or third laptop at all...
 
Comparable in the 100s of milliwatt range

electronics.stackexchange.com

Current over ethernet?

It seems that the voltage over ethernet ranges from 2 to 3 volts. How much current typically runs through the wires? I tried Googling with no success. I ask this because I'm looking for components...
electronics.stackexchange.com electronics.stackexchange.com
 
zsolt said:
If you are concerned about the savings how about don't use the second or third laptop at all...
Click to expand...
Since I have 7 laptops in my living room...
But 4 are powered on at once, at most.

I think I will need to make some measurements myself. The scenario is like this: you have one of these newer models which don't have a NIC any more. So a) go for wireless or b) turn off the WLAN of the router and use cable+docking. Since I have a power meter somewhere I will check this out when I have the time.
 
Kill-a-Watt is what I use for amperage. They last a good long time.

I was really surprised by the difference in i210 versus i350 from that Intel page
.8watt versus 4.4watts.
I believe i350 carries server features found on 10G fiber cards like SR-IOV.
How it could use 5x the power I dunno.
 
Some data:
Laptop: Ideapad 3, running 13.1
Laptop idle: 4W
Laptop downloading Wifi (2MB/s) 5W
Cable modem with and without WLAN active, idle: no difference.
Removing second AP (matchbox sized), idle: -2W (!!)
Cable modem with load commingg tomorrow.
 
More Data, this time with my x230 as it has a RJ45,

Cable modem idle:11.1W x230 idle 12.5W (acpiconf -i 0)
Downloading 13.1 for RPi WIFI : Cable modem 12.9W x230 16.5W

Switching WIFI off in the modem, connecting cable...

Cable modem idle:11.4W x230 idle 13.5W (acpiconf -i 0) <-- Wut?
When the cable is connected, power consumption of the modem goes up from 10.8 - 10.9 up by half a W. The Laptop goes up by a W also, from 12.5 to 13.5. As soon as DHCP ran, and the interface actually had a link - 11.4W modem, 14.2 Laptop.

Disable wlan0 device, laptop now at 12.2W

Downloading 13.1 for RPi copper : Cable modem 11.7 laptop 14.5W

So what have we learned?
(Posting this for backup purpose as the machine cold booted at re-docking mid-writing)
 
Crivens said:
More Data, this time with my x230 as it has a RJ45,
Click to expand...

For some comparison, I have here an X200 (2.4GHz C2D) and a T430s (2.6GHz i5), both with RJ45 and iwn wifi, but via a phone hotspot, so I'll just quote wifi off/on data.

Crivens said:
Cable modem idle:11.1W x230 idle 12.5W (acpiconf -i 0)
Downloading 13.1 for RPi WIFI : Cable modem 12.9W x230 16.5W
Click to expand...

X200 idle 800MHz, wifi switch off 9.3W, on 10.1W, but not currently using wifi.

T430s idle 1200MHz, wifi switch off 12.6W, on 14.2W, connected.

Crivens said:
Switching WIFI off in the modem, connecting cable...

Cable modem idle:11.4W x230 idle 13.5W (acpiconf -i 0) <-- Wut?
When the cable is connected, power consumption of the modem goes up from 10.8 - 10.9 up by half a W.
Click to expand...

Er isn't that 0.1W? About all I'd expect for ethernet (idle).

Crivens said:
The Laptop goes up by a W also, from 12.5 to 13.5. As soon as DHCP ran, and the interface actually had a link - 11.4W modem, 14.2 Laptop.
Click to expand...

Interesting, surprising even. Sometimes need patience with acpiconf data, settling time, asynchronous probes?

Crivens said:
Disable wlan0 device, laptop now at 12.2W
Click to expand...

Disabled by power switch or software devctl(8), disable or suspend?

Crivens said:
Downloading 13.1 for RPi copper : Cable modem 11.7 laptop 14.5W

So what have we learned?
(Posting this for backup purpose as the machine cold booted at re-docking mid-writing)
Click to expand...

Another factor is time: here, ethernet clearly uses far less power than wifi, not least because apart from the odd keepalive packet, it's mostly idle. Wifi OTOH is nearly always busy all day doing nothing much at all ...

OS tuning will win more power savings than either. I have another X200 to replace the above one which has a CPU fan that usually fails on boot, meaning any intensive use shuts down at 100C.

However it's running a so far untuned 12.3-RELEASE, the older one is 9.3-STABLE; the difference at idle is the above 9.3-10.1W versus 12.3-12.7W!
 
Seems to depend on the actual hardware

LAN disabled in BIOS8.6
LAN enabled, down, not connected9.3
LAN active9.3
WLAN disabled-"-
WLAN enabled, down9.4
WLAN associated9.6

Lifebook A3511 (not much optimized)
LAN = RealTek something
WLAN = Intel AX 201

This RealTek piece seems not to have power saving logic and always runs at full load when enabled.
 
in wireless network you have encryption and in low SNR you have more retransmissions and increased latency which cause additional power consumption compared to the ethernet.
 
IMHO you are always better served when using an eherternet cable as it is a more security and knowledge of knowing that you will always have a guaranteed connection , as WIFI connections can both crap out and leave you valuable to ill meaning people hacking your network even if you' use the latest security standards which even though they are supposed to be quiet abit more secure than their earlier cousins such as wep or wpa+psk first generation.
 
Crivens said:
The power line measurement device kept bouncing between 10.8 and 10.9W.
Click to expand...
Ah, I see what you meant.

Crivens said:
Ifconfig wlan0 down. The x230 has no hw switch.
Click to expand...
Mildly surprising when the x200 does. RH side front on the t430s, maybe an 's' thing.

I should take PMc's point and disable LAN in BIOS, only wifi here at the moment. Just remembered, I might have WoL enabled on the em0 too!
 
smithi said:
Mildly surprising when the x200 does. RH side front on the t430s, maybe an 's' thing.
Click to expand...
Now I went looking with a flashlight, and it has one smaaaaal switch left side, right side front in at the edge.
I can't check it right now as I am hosting a minetest for the kids. If the switch works, there will be tears at once.
 
Crivens said:
Now I went looking with a flashlight, and it has one smaaaaal switch left side, right side front in at the edge.
I can't check it right now as I am hosting a minetest for the kids. If the switch works, there will be tears at once.
Click to expand...
Sounds like the one; on the x200 it shows green (paint) when on, slid toward front.

Don't cry, count the extra minutes on battery of 0.8W!

What CPU on the x230? i5?
 
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