It was hard to decide if to post here or on Green computing hope this is the right way.

I have purchased a used NEC 2090UXi monitor an I have an Acer X203w monitor both are 20" but NEC is 4:3 and Acer is 16:10 so NEC has a bit bigger screen.
I decided to do some power consumption test since this is important for me and I also did some image comparison test see photos.
Acer is using a TN (Twisted Nematic) panel as 90% of the LCD on the market today they have better response time than the other technologies (so are good for games) but they only have 6 bit / color = 18bit in total so 262k colors in total and they use dithering to get 16M colors I have a problem with this I will explain later.
NEC is using a A-TW-IPS (Advanced true white In Plane Switching) panel more expensive and not as fast as TN but better color accuracy since is 8 bit / color so 24bit in total and sporting native 16M colors.
The problem with TN panels for me is that are hard on my eyes since they use dithering the color accuracy and better viewing angle is not so important for me but is good to have.


One interesting fact is that the NEC uses less power with a black screen vs Acer that uses more with a black screen than a white one.
The contrast will not affect the power consumption.
I can use the NEC at 20% but to get the same visual effect I need the Acer at 50% brightness so the power consumption is not to different.
The real power (Watt) is equal or less than apparent power (VA) but for now I have no possibility to measure PF (power factor).

Now come photos with the colors and viewing angle.
I clear that Nec is a superior monitor but also the price is 4 to 6x higher so is to be expected.

First 3 photos are with the standard colors.

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Next photos are after I was trying to get the same colors on the Acer basically I reduced the blue to 25% the RED and GREEN where default at 50%

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Those are two very different monitors, intended for different usage. The NEC was intended to be used for professional graphics applications like photo editing, and the Acer is an inexpensive general purpose monitor. I have an NEC 2070NX, which was a lower priced graphics monitor (also with an IPS screen). Probably the primary reason that the NEC is easier on our eyes is because it has a lower pixel pitch than the Acer.

No the pixel pitch is about the same 0.250 vs 0.255 the problem is that on the TN panel to get the 16M colors the pixels are flickering at high frequency so if you look very close to a gray (one of the color that can not be reproduced with 6 bit/color) image you will see that on TN panel will have something similar to a noise you need to be two inch close to see this effect but i think this is the reason Acer TN is harder on the eyes.
Look at this test especially at the square 6 to 15 on a TN screen this will not be clean but noisy because of dithering trying to create a non native color. The effect I see on the Acer is Temporal dithering. explained in the test page.