It is currently Sat Sep 20, 2014 5:16 am

All times are UTC - 8 hours




Post new topic Reply to topic  [ 12 posts ] 
Author Message
 Post subject: White power reduction
PostPosted: Wed May 30, 2007 3:25 pm 
Offline

Joined: Fri Jan 20, 2006 10:12 am
Posts: 545
Location: UK
I bought one of those nifty plug-in mains wattmeters, so I can test a few theories now. One of these is that since LCDs default to transparent when power is removed, that displaying a white screen will use less power than a black screen. That's the theory anyway, but lets see what the meter says:

The first test subject is an NEC LCD1770NX.

Code:
Black screen: 24W
White screen: 23W


Interesting. How about an LG L1715S?

Code:
Black screen: 26W
White screen: 25W


So there you go. It really works! It's not exactly a spectacular difference, but maybe it's enough to make lighter desktop backgrounds a little more attractive now.

_________________
https://mrevil.asvachin.eu/


Top
 Profile  
 
 Post subject:
PostPosted: Thu May 31, 2007 7:23 am 
Offline

Joined: Fri Nov 08, 2002 4:05 pm
Posts: 133
Yeah, somebody did a plugin to have a black google, and figured out how many tons of CO2 a year it would save if google made their own page black. I think that people should use whatever is comfortable for them. Don't use pure black on the background if you have a second monitor (without the taskbar), as you might forget to turn it off, thinking it is already off. I did that one day for a few hours, now I use the black dl.tv background, so that I know if the monitor is on.


Top
 Profile  
 
 Post subject:
PostPosted: Thu May 31, 2007 7:34 am 
Offline

Joined: Fri Jan 20, 2006 10:12 am
Posts: 545
Location: UK
Bigg wrote:
Yeah, somebody did a plugin to have a black google, and figured out how many tons of CO2 a year it would save if google made their own page black....

No, this is the other way around. Old CRT monitors may have used less power when displaying black, but LCD monitors use less when displaying white! Since you can hardly even buy CRT monitors anymore, the old way is now obsolete.

_________________
https://mrevil.asvachin.eu/


Top
 Profile  
 
 Post subject:
PostPosted: Thu May 31, 2007 9:30 am 
Offline

Joined: Fri Nov 08, 2002 4:05 pm
Posts: 133
So, basically, it just doesn't matter.


Top
 Profile  
 
 Post subject:
PostPosted: Thu May 31, 2007 10:30 am 
Offline

Joined: Fri Jan 20, 2006 10:12 am
Posts: 545
Location: UK
A 1W difference is small, but it does exist. If your computer uses little power already, then it might be a difference that is worth thinking about, at least.

_________________
https://mrevil.asvachin.eu/


Top
 Profile  
 
 Post subject:
PostPosted: Thu May 31, 2007 10:37 am 
Offline
SPCR Reviewer

Joined: Fri Mar 04, 2005 9:07 pm
Posts: 1027
Location: Vancouver
Only CRTs use more power when displaying white.


Top
 Profile  
 
 Post subject:
PostPosted: Thu May 31, 2007 10:50 am 
Offline

Joined: Mon Feb 05, 2007 4:14 pm
Posts: 219
Location: Forkbomb, New South Wales
The numbers posted are interesting, but are not distinguishable from randomly generated numbers, even at very low confidence levels. In order to be sure it actually makes a difference, you'd have to take samples from ~1200 LCD's. Even a modest increase in samples, like 100, could be enough, however.


Top
 Profile  
 
 Post subject:
PostPosted: Thu May 31, 2007 1:03 pm 
Offline
SPCR Reviewer

Joined: Sun Aug 11, 2002 3:26 pm
Posts: 3998
Location: Phoenix, AZ
I would be willing to bet that world-wide there are still many more CRT monitors in use than there are LCD's.

_________________
Senior Contributing Writer, SPCR


Top
 Profile  
 
 Post subject:
PostPosted: Thu May 31, 2007 3:26 pm 
Offline

Joined: Fri Nov 08, 2002 4:05 pm
Posts: 133
Rusty075 wrote:
I would be willing to bet that world-wide there are still many more CRT monitors in use than there are LCD's.


Probably true, especially in other less affluent countries. I know my school has mostly CRTs. I have two CRTs in mainline service and one LCD, not counting a pair of laptops. I have a bunch more CRTs in secondary service in the basement for "testing" (playing with Linux or something).


Top
 Profile  
 
 Post subject:
PostPosted: Thu May 31, 2007 4:03 pm 
Offline

Joined: Tue Jan 04, 2005 4:02 pm
Posts: 1608
Location: United States
Makes sense, LCD panels display color by blocking light. When the screen is white it isn't blocking any light, when black it's blocking all the light (technically not all, one of the weaknesses of LCD technology). :)

But the numbers do support the premise that the backlight is the biggest power consumer in the LCD. The actual LCD panel itself must consume next to nothing if the difference between fully blocking and not is less than a watt.

_________________
Corsair Obsidian 650D | Seasonic X-650 | Gigabyte GA-990FXA-UD5 | Phenom II X4 955 | Noctua NH-D14 | 2x4GB Corsair DDR3-1600 | ASUS HD6950 DirectCU II 2GB | OCZ Vertex 2 120GB | 2x WD Green 1TB


Top
 Profile  
 
 Post subject:
PostPosted: Thu May 31, 2007 5:51 pm 
Offline

Joined: Fri Nov 08, 2002 4:05 pm
Posts: 133
frostedflakes wrote:
Makes sense, LCD panels display color by blocking light. When the screen is white it isn't blocking any light, when black it's blocking all the light (technically not all, one of the weaknesses of LCD technology). :)

But the numbers do support the premise that the backlight is the biggest power consumer in the LCD. The actual LCD panel itself must consume next to nothing if the difference between fully blocking and not is less than a watt.


Hopefully that power will come way down with LED technology. :D


Top
 Profile  
 
 Post subject:
PostPosted: Sun Sep 16, 2007 9:02 pm 
Offline

Joined: Fri Aug 19, 2005 6:22 pm
Posts: 50
Location: North Hollywood, CA, USA
This is an important issue with LCDs. Do not use black screensavers - they aren't saving anything!

You do save 1watt, but much more importantly you preserve the life of the liquid crystals, leading you to not throw that monitor - or laptop - away as soon. That has a very significant savings to the environment. Plastics and poisonous metals staying out of the ground is a good thing. The energy required to manufacture your next monitor is also postponed, leading to less overall energy usage - by quite a bit - in your lifetime.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 12 posts ] 

All times are UTC - 8 hours


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group