monitor power consumption

I got a ViewSonic VP2030b today, and given all the recent commotion about, I figured I would verify the claims in Google’s blogpost.

Description Brightness Power consumption
Sleep mode (no signal, orange light) or switched ‘off’ with the front switch N/A 0.01A at 120V (1024×768) 100% 0.69A at 120V (1024×768) 100% 0.68A at 120V (1024×768) 50% 0.58A at 120V (1024×768) 50% 0.58A at 120V (1600×1200) 100% 0.71A at 120V (1600×1200) 100% 0.69A at 120V (1600×1200) 50% 0.60A at 120V (1600×1200) 50% 0.58A at 120V

These measurements were made with Firefox in full-screen mode (F11). The built-in USB hub was not connected to the computer.

As you can see what Google says is correct for this 20″ LCD monitor at 1024×768 resolution: there is no difference in power consumption between and However, at native resolution (1600×1200), there is a small difference in power consumption (0.02A). Most people can be expected to run the monitor at this resolution.

The effect of changing the brightness is much more pronounced than the difference between Blackle and Google (previously I erroneously mentioned that changing the brightness had no effect; I was in fact changing contrast, the on-screen-menu for this monitor is not the most userfriendly).

Viewsonic claims a typical power consumption of 52W, which is very close to what I’m seeing here at 1600×1200 with brightness set to 100% (48W). But the VA value is 85, which means this monitor has a pretty crappy power factor (PF) of 0.56. Compare that with the Antec EarthWatts 380 power supply I bought for this new computer, which has a PF of 0.99! The wikipedia page on power factor correction is pretty fascinating reading if you want to know what Viewsonic could have done to improve the power factor.

The ‘sleep’ power consumption is not so bad at about 1W, but I will still switch the thing off when I’m not using it. One Watt 24/7 is over 8.5 KWhr per year, which is a lot of energy to waste.

The monitor has a power off switch on the front, but that makes no difference in terms of power consumption compared to sleep mode; it still sips 0.01A. Fortunately there is a real off switch at the back next to the power plug as well.

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