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Ethernet Card as major heat source? - Elf M. Sternberg
Ethernet Card as major heat source?
My laptop runs incredibly hot, but I've noticed that it runs even hotter at the office. As far as I can tell, the only difference between that work environment and my home environment is that at the office I have an ethernet cable, and not WiFi. Could that really be the major heat source, contributing as much as 10C of extra heat to the laptop under normal operating conditions?

Current Mood: annoyed annoyed

11 comments or Leave a comment
autopope From: autopope Date: March 21st, 2011 05:41 pm (UTC) (Link)
Consider the logic thus: if the laptop is plugged into an ethernet cable, then it is very probably plugged into a wall jack and is in an office where there are mains sockets. Therefore it is probably running off juice and power management is less critical than when on wifi (and, by implication, battery).
(Deleted comment)
blaisepascal From: blaisepascal Date: March 21st, 2011 07:32 pm (UTC) (Link)
I think autopope is suggesting that the causal effect is mains->hot/battery->cool, and there is a correlation between ethernet<->mains and wifi<->battery. So while the observation is ethernet->hot, it's really ethernet means more likely to be on mains, and mains causes heat versus wifi means more likely to be on battery, and battery causes cool.
autopope From: autopope Date: March 23rd, 2011 02:10 pm (UTC) (Link)
No. My reasoning is that the idiots who wrote the driver for the wired ethernet chipset probably didn't bother their little heads about power management because they assumed it'd always be plugged into the mains while it was throwing packets hither and yon.
From: (Anonymous) Date: March 21st, 2011 07:30 pm (UTC) (Link)
What's the ambient temperature in both places?
mouser From: mouser Date: March 21st, 2011 08:01 pm (UTC) (Link)
Are you turning off the WiFi when you're on hardline?
alicephilippa From: alicephilippa Date: March 21st, 2011 08:06 pm (UTC) (Link)
Most laptops these days put the ethernet card in low power mode (essentially switched off) when it's not got a cable plugged in. So, there's one source of heat you don't have at home.

Another is that if you are using it off battery at home the system will use assorted power management features (adaptive CPU clock speed, for example) to reduce power consumption. Running of the mains usually these power saving features are disabled and more power is consumed and more heat generated.
voidrandom From: voidrandom Date: March 21st, 2011 11:11 pm (UTC) (Link)
Is it possible that there is more network traffic at work and that is just working the ethernet chips harder? Even a packet not addressed to the local machine has to be examined before it's ignored.
wolfwings From: wolfwings Date: March 22nd, 2011 08:24 am (UTC) (Link)
I could actually see gig ethernet causing a fair bit of temperature spiking in a localized area since it's four 250Mbit transceivers along with noise-cancelling hardware that needs to be running to support full-duplex on all pairs, versus 100Mbit that's a single 100Mbit transmitter and a single 100Mbit receiver.

Try locking the laptop down to 100Mbit and see if that makes a difference?
elbowfetish From: elbowfetish Date: March 22nd, 2011 08:53 am (UTC) (Link)
The wired and wireless NICs could each draw a few Watts, but not very much compared to your RAM, CPU, disk & display. I'd expect more variation from different thermal properties of the desktop surface, different angle the display is at, less ventilation around the fan port... An aluminum pad under the laptop might cool it right down. Or drink 4 beers first thing at the office and prop it up on the cans.

I tried to BING it but the first relevant link that came up was this thread. :-)
pakraticus From: pakraticus Date: March 22nd, 2011 03:16 pm (UTC) (Link)

It isn't the ethernet, it's just running off the wall current...

1) Usually power saving settings get turned off when on wall current.
2) Topping off the battery generates huge amounts of heat.
gromm From: gromm Date: March 22nd, 2011 06:44 pm (UTC) (Link)
I've recently heard that there's a couple of other sources of heat that you probably aren't considering:

1. Wireless sources, like proximity to cordless phones, wifi, and microwave ovens.
2. Shiny desk surfaces that actually reflect infrared radiation back into the laptop.

I would suspect 2. before I suspect 1. at your workplace however. 2. is often counter-intuitive for laptops, since hard surfaces usually work better for airflow than soft ones like your lap or sofa.
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