Low Power Monitors from Samsung and Lenovo

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Samsung P2070 and ThinkVision L1940p Wide

October 7, 2009 by Devon Cooke

ThinkVision L1940p Wide
19" Widescreen LCD Monitor
Samsung P2070
20" Widescreen LCD Monitor
Street Price

Monitors are not our usual review subjects at SPCR. Ironically, the fact that they make very little noise (with a few exceptions) takes them off our radar; they're generally quiet and we like that, but we don't have too much else to say. That said, our interest in power efficiency (and some corresponding environmental concerns) has prompted us to take a closer look at a couple LCD monitors that bill themselves as "low power". (Editor's Note: CFLs and other electronics inside modern monitors do often exhibit high pitched whining or buzzing sounds, as our Quiet / Noisy Monitor Survey has helped to document for the past year. However, the monitors reviewed here did not exhibit any audible noise.)

The first is from Lenovo, and some work has clearly been put into engineering a product that is kinder to the environment. The monitor complies with a number of environmental standards, including EPEAT Gold certification. The monitor first got our attention as part of Lenovo's ThinkCenter M58p small form factor computer, where it impressed us enough to take a more detailed look at it here.

The second is a Samsung, and while the marketing emphasis is certainly less environmentally-centered than the Lenovo, the power rating does look pretty good.


Lenovo's look is all business.

Power rating aside, the two monitors don't have a whole lot in common. As you would expect of Lenovo's business market, the L1940p is black, utilitarian, and businesslike. It offers practical features like a height-adjustable stand, a 90° pivot for use in a "portrait" format, and a means of hiding cables in the base. The buttons are large, easily accessible on the front bezel, and contoured so they can be found easily by touch. The appearance is a little stodgy, but perhaps that's to be expected in a product line with a century's worth of business machines behind it. What it lacks in sexiness, it makes up for in a feeling of solidity and quality. It adheres to the practical, utilitarian design principles that we often espouse at SPCR.

The stand is very flexible, allowing both height and orientation to be changed.

The five control buttons are large and accessible.

Despite its business simplicity, there are a few nice touches that make the L1940p feel like a complete package rather than a budget buy. It features both analogue (VGA) and digital (DVI-D) inputs, as well as a socket for a Kensington security lock for public installation. The height-adjustable stand is worth mentioning again. The head of the stand is highly flexible, allowing 45° of left-right swivel in each direction, 30° of vertical tilt, and the aforementioned"pivot" that allows the screen to be used at a 90° angle (though your graphics card will need to support a similar function unless you are adept at reading text vertically). If all that flexibility isn't enough for you, it is also compatible with a number of third-party mounts for wall-mounting and other exotic positions.

Both VGA and DVI are supported, and cables can be hidden in the stand.

Specifications: Lenovo L1940p
Panel Size
19" Wide
Aspect Ratio
Screen Dimensions
408.2 mm (W) x 255.2mm (H)
Pixel Pitch
0.285 mm
Dot / Pixel Per Inch
250 cd/m²
Contrast Ratio
1000:1 (typical)
Viewing Angle
(HxV @ CR 10:1)
160° / 160°
Response Time (Typical)
5 ms
Panel Type
twisted nematic, CCFL backlight
Power Consumption
(Typ. / Max / Sleep)
16W / 23W / <1W
Video Input Signals
Analog + DVI-D (HDCP)
Cables Supplies
Analog + DVI-D
TCO'03, EPEAT Gold, GreenGuard, Energy Star 4.1, RoHS, Windows Vista, ISO DIS 13406-2
Tilt Angle (front/back)
0° / 30°
Swivel Angle (left/right)
4.33" / 110mm
VESA Mount
Yes (100 mm)
Kensington Lock Slot
Dimensions (WxDxH)
440.2 x 241.5 x 356.1 mm
5.80 kg / 12.79 lbs

Technically, things seem pretty standard. It has a 19" screen (a bit small by today's standards) with a 16:10 aspect ratio and a native resolution of 1440x900. Contrast is rated 1000:1 (typical), and response time is 5 ms. The one spec that stands out is the one that caught our attention in the first place: Power consumption. This is rated at 16W (typical) / 23W (max), which is significantly better than the 30+ W that we expect of LCD monitors. We'll see how accurate this is when we get to our test results.

Lenovo has clearly put some effort into getting the monitor recognized as an environmentally friendly choice. Aside from the EPEAT Gold certification we mentioned already (more info in this article on Eco PC Review), it also proudly displays compliance with TCO'03, RoHS, and, interestingly, something called GreenGuard. GreenGuard is a little outside of our area of expertise; the products they typically certify appear to be building materials. Although they do have an electronics category, Lenovo is the only company with certified products so far. The certification is for air quality — specifically, with respect to potentially harmful chemicals that may leach into the air from the products they certify. They have a document that extensively outlines their test methodology, but it is a little beyond the expertise of this reviewer to comprehend.


Color fidelity was tested by comparing a slate of ten original photographs with a high quality (if aging) imaging monitor, a Viewsonic G225f, calibrated with a Datacolor Spyder 2 monitor color calibration device, the previous generation of the Spyder 3. The L1940p was tested with various color profiles engaged, including a corrected profile calibrated in software using the Spyder 2. This corrected profile was used to see how good the monitor's color could potentially be, rather than to evaluate its color performance out of the box.

Reference photos were taken of the Lenovo's color reproduction, with the camera white-balanced to a solid white screen on the calibrated reference monitor (nominally 6,500°K). This ensured that, as far as possible, color variances could be attributed to the monitor, not the camera. Due to differences in brightness across the various monitor profiles, exposure was not corrected for in the camera, some artifacts related to brightness (notably the darker shadows in most shots) can be seen that are not monitor related.

"Original" is the uncorrected original photo. "Stock color" shows the color out-of-the-box (neutral setting). "sRGB" was the most natural looking default setting, and "Corrected" shows how the monitor looked after correction with the Spyder 2 calibration device. Note the stark whiteness of the granite in the uncorrected versions rather than the subtle earth tone in the original and corrected versions.

The L1940p includes four basic color profiles: Neutral, Reddish, Bluish, and sRGB. sRGB (the standard color space for monitors) looked the most natural, but natural is a relative term; all four default profiles looked very blue — even the "reddish" profile. sRGB also looks slightly greener than the other profiles. As often seems to be the case with monitors, all of the profiles seemed to exaggerate both contrast and color saturation. None of the default settings would be acceptable for color-sensitive work.

After calibration with the Spyder 2, the color looked much more natural, though there were still a few minor deviations from the reference monitor, notably exaggerated color saturation and a loss of detail in heavily saturated reds that can probably be attributed to a smaller color gamut. Nonetheless, L1940p is not intended as an imaging monitor, so these deviations are fairly minor. In the vast majority of situations, the corrected color is probably good enough for everyday use.

Here, the most noticeable effect in the uncorrected versions is the disappearance of the golden sunshine on the mountain and the downpipe. The uncorrected settings look colder thanks to the heavy blue emphasis. The added green in the sRGB setting gives the sky a bit of a technicolor look that is pretty but unnatural.


Power consumption is tied to the amount of light the monitor must produce, so power was measured several times with the monitor in two states: pure white and pure black. Power was measured at the wall with a Kill-a-Watt AC power meter.

Lenovo L1940p Power Consumption
Setting Screen Output Power Consumption
80 Brightness
50 Contrast
Black 14W
White 13W
64 Brightness
63 Contrast
Black 11W
White 11W
0 Brightness
0 Contrast
Black 8W
White 8W
100 Brightness
100 Contrast
Black 17W
White 17W

With the exception of the "maximum" test, every single measurement we took bettered Lenovo's average power consumption spec — and even that was only a watt over. The calibrated result of 11W was certainly the best we've ever seen for a stand-alone monitor. It's quite likely it would be beaten by an integrated (and much smaller) laptop screen, but it's pretty darn impressive for a stand-alone product.

Whether the screen was black or white did not appear to matter much for the L1940p. This indicates that most of the power is being consumed by the CCFL backlight, not the LCD technology itself. One thing that confused (and pleased) us a little was how much lower our measurements were than the peak power specified by Lenovo.

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