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CCFL Versus LED: Is There A Downside To Going Green?

Asus Power Draw

Let’s start by examining our Asus trio. To be honest, this article began many months ago with some considerable dialog between Asus and ourselves. The two MS-series monitors were the first units we tested, and it was with them that we devised our first power testing methodology.

Black and white screen tests are pretty self-explanatory; we used an empty MS Word 2003 document at full-screen with no toolbars showing to create the white display while full-screen back was done by having a Windows screen saver show only 100% black. For video testing, we ran a two-minute clip from “Sherlock Holmes” and took the average power draw value as measured by a Belkin Conserve energy monitor sitting between the display and the wall.

LEDCCFLCCFL
Monitor TestAsus MS238HAsus MS246HAsus VW246
Blank screen saver29.3 W29.9 W44.8 W
Video, 100% brightness28.9 W29.0 W44.8 W
Video, 75% brightness25.6 W25.4 W38.5 W
Video, 50% brightness22.3 W22.3 W32.1 W
White, 100% brightness27.7 W27.2 W43.8 W
White, 75% brightness24.4 W23.7 W38.1 W
White, 50% brightness21.2 W20.6 W31.4 W
Black, 100% brightness28.9 W29.1 W44.3 W
Black, 75% brightness25.6 W25.6 W38.4 W
Black, 50% brightness22.4 W22.5 W32.0 W

The first thing that jumps out here is that the two MS models live up to their spec sheets’ promises of similar power consumption. Even if the vendor spec of a 33 W maximum proved pessimistic, the differences in draw in all of our scenarios are effectively nil. Yet one uses LED backlighting and the other CCFL. Huh?

We immediately sent these early results back to Asus' team, which reported that “the product manager is quite surprised also.” We suspected that the power circuitry must be the actual determiner of power consumption, and not the backlight technology. Further inquiry yielded this official reply: “Actually, [the product manager] was surprised that nobody had asked the question before now. Yes, the MS series uses the same electronics regardless of panel type, so their base energy consumption numbers will be the same.”

This bombshell was validated when we received the VW246 and confirmed that it indeed sucked down roughly 50% more energy than its CCFL-based cousin.

As for power numbers, another interesting point leaped off the spreadsheet. In retrospect, we should have guessed it all along, but so many years of using CRTs caused us never to question the assumption that black was better. Black saved energy. That’s why we have Blackl.com (yup, still running) for all those users who have Google Search as their home page. But in the LCD world, where LCD matrices must apply voltage in order to twist the crystals within a panel cell in order to block the backlight from shining through, black is bad. Black wastes energy. This is why a screen showing HD video usually consumes less energy than the same screen sitting at a black Windows desktop. Often, the most energy inefficient thing you can do is run a blank screen saver, that old power-saving standby from the CRT era. Things change.

As you can see, there’s a significant difference—30% to 40%—between running a screen at 100% brightness versus 50%. If you reach out to your display right now and dial back the brightness from 100% to 50%, it’ll probably look very gray and muddy to you. Most of us have become accustomed to 100% brightness, but that’s actually a lot like letting your car engine idle at higher RPMs. In reality, you’re not going to drive any faster; you’re just wasting gas.

  • In the "Wrapping It Up" section, perhaps you meant "LED" instead of "LCD"?
    Reply
  • nevertell
    How about doing this with IPS panels ? :>
    Reply
  • nforce4max
    I am going to get such a monitor later this year. Imagine the leap from CRT to Led LCD.
    Reply
  • Ragnar-Kon
    I personally can't wait until the OLEDs manufacturing process becomes cheaper. Having seen Sony's new OLED displays at this year's NAB in Vegas, I can say they are VERY VERY impressive.
    Reply
  • scook9
    I know that I have been rocking a pair of Gateway FHD2400's for a few years now and love them as they meet all my needs and have never left me wanting
    Reply
  • g00b
    Ummm ... LED? They are all LCD :).

    "Ultimately, we’d pick LCD for media consumption, but we’d pick CCFL for editing work where detail and accuracy are paramount. LCD is more fun to watch; CCFL is more reliable."
    Reply
  • Please substitute "LCD" with "LED" everywhere in the conclusion section!
    Reply
  • theshonen8899
    Basically the differences are very dramatic right? I'm gonna sound like a hippie for this but I'd definitely go for the greener option. Just being polite for our future generation is all.
    Reply
  • what g00b said. At the end you start saying LCD instead of LED, might confuse some poor soul.
    Reply
  • wrxchris
    May not be too relevant here considering that this article was based around image quality, but as a gamer, I'm still plenty satisfied with my trio of 25.5" Asus TN monitors. Yes, they bleed a bit of light around the edges and the colors may not be very accurate, but they handle fast moving images with no problems and only cost $750 for the set. And my favorite feature is the 16x10 aspect ratio, which is becoming quite hard to find these days; not sure why people are so willing to give up vertical screen space.
    Reply