The Monitors: Asus, BenQ, Dell, Samsung, and Viewsonic

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.

The first thing that jumps out 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.

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.

BenQ And Dell

There’s no point in trying to be clever about explaining why we only have one BenQ model here. Its presence (as well as Viewsonic’s later) serve to help corroborate our observations of the semi-matched pairs from Asus, Dell, and Samsung. BenQ and Viewsonic would be more useful with their CCFL or LED twins, respectively, but there simply weren't any available to test.

From a power perspective, BenQ’s EW2420 is the highest energy consumer among our LED models. Could this be a result of the VA technology BenQ implemented to deliver a superior viewing experience? Perhaps. We’ll see if BenQ’s VA panel delivers on its visual promises in a bit. For now, it’s interesting to note that the BenQ is the only monitor we tested that showed higher power draw at 100% brightness running video and a white Word screen than a black screen saver.

Now, how about those Dells? We saw earlier that the pair showed identical power specs on paper. Dell’s 30 W maximum draw turns out to be a little pessimistic, as the highest draw we saw from either unit was 26.4 W from the ST2320L at a black screen. At 50% and 80%, the two displays are essentially identical on energy use. At 100%, though, the CCFL-based ST2310 averages about 2 W less than the ST2320L in each test.

How is this possible? Whereas every other CCFL monitor in this roundup uses four lamps, the ST2310 only uses two. The fact that we had to get this explanation from Dell, and couldn’t observe a visible difference at first glance, may give you a hint as to what’s coming.

Apart from Dell competing with itself, both Dell monitors easily trounce their competition on power consumption, often by 10% to 20%. We don’t have an explanation on why Dell’s monitors are so much more efficient than rival brands, but it’s clear that the company’s growing reputation in the display space is well-deserved.

Samsung And Viewsonic

The first thought that crossed our minds when testing the Samsung BX2350 was that it looked eerily similar to the Asus MS238H. At 100% brightness, the two are essentially indistinguishable. Given that there are only a handful of true panel manufacturers on the planet, we wouldn’t be surprised if both companies were using the same glass. With the BX2350 selling for $260 on Amazon as of this writing, and the MS238H floating around at $170, you can examine Samsung’s perks and see for yourself if they add up to a nearly $100 price premium.

Similarly, the Samsung P2350 lines up very evenly with Asus' VW246. The Samsung pair is our best representation in this roundup of a typical old versus new tech match-up. The CCFL design clearly lags LED by 55% on total draw across all test scenarios. So, are Viewsonic’s claims of 50% savings typical of what we should expect from LED monitors in general? Absolutely. Our widest divergence from Samsung was 62%. Relatively speaking, that’s a massive advantage. If you’re saving 15 W per screen in a triple-head display that runs 15 hours per day at 12 cents per kilowatt-hour, that’s a $30 annual savings on your electricity bill. Over the life of the triple-head rig, you’ll likely save enough to pay for one of the monitors. That’s not bad, especially if the screen looks better than its CCFL alternative. But let’s not jump to conclusions just yet.

At this point, we had a chance to query an unnamed BenQ product manager about our power assumptions and findings so far. This is what we received in reply:

1. Power savings of up to 80% sounds amazing, but you’re not going to get that from the LED backlighting alone. For most LED applications, we rarely see power saving benefits up to that much.
2. CCFL structure efficiency is less than with LED circuits. For example, the efficiency of the “converter” for LED is around 90%, while the “inverter” for CCFL is around 80% to 85%. In other words, not only does LED contribute to power savings, but the structure of the power circuit does this, too.
3. In reality, four-lamp CCFL consumes more power than LED, but for two lamps, it consumes similar power as LED. That is because of the contribution from optical film inside the two-lamp backlight unit.

As for Viewsonic, power results are in line with what we would now expect from a conventional CCFL display. In fact, the VG2428wm undercuts the Asus and Samsung CCFL options by a significant margin. So, while we can debate whether Viewsonic should have followed Dell with a two-lamp design, we’ll at least compliment the company for doing a better job than most with the four-lamp option it delivered.