Dell U2311H
Simon Baker, 5 June 2010

 

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The news of two new screens from Dell broke early in May when details of a new 21.5" and 23" model appeared on Dell's Asian websites. We reported at the time about the new U2211H and U2311H and readers were immediately interested in the use of IPS panel technology again. As Dell have done with the rest of their Premium UltraSharp monitor range, they have opted to use high end IPS technology to offer good all round performance and meet the demands of the public who are turning away from TN Film more and more. Dell now have the 2007FP (20"), 2007WFP (20"WS), U2211H (21.5" - review coming soon!), 2209WA (22"), U2311H (23"), U2410 (24"), U2711 (27") and 3008WFP (30"), all of which use this panel technology. We've already taken a look at the 24" and 27" models, but we now have the 21.5" and 23" models with us for testing.

We'll start by taking an in depth look at the 23" U2311H which is already attracting a great deal of interest in the market. The U2311H follows in the footsteps of the popular NEC EA231WMi which is bound to draw direct comparisons. We'll compare the two models later, but Dell have opted to use the same LG.Display e-IPS panel in their new display. Interestingly, and importantly for some users, the U2311H also features only a standard sRGB colour space, unlike its bigger 24 - 30" brothers. There's still a demand for standard gamut screens in the market, and like the NEC, this new model tailors to that requirement.

Let's start by taking a look at the specs for the U2311H:

Size

23"WS

Colour Depth

16.7 million (6-bit + AFRC)

Aspect Ratio

16:9

Colour Gamut

72% NTSC colour gamut, 100% sRGB

Resolution

1920 x 1080

Viewing Angles

178/178

Response Time

8ms G2G

Panel Technology

e-IPS

Contrast Ratio

1000:1 static / 10,000:1 DCR

Interfaces

DVI-D (HDCP), D-sub, DisplayPort

Brightness

300 cd/m2

Colour

Black bezel and base with silver trim

Special Features

Tilt, pivot, rotate and height adjustment. USB 2.0 ports x4

Buy

PCBuyIT

 


Above: Front and rear views of the screen. Click for larger versions

Like the U2410 and U2711 we have already seen, the U2311H has a fairly subtle but professional look, with a thin black bezel around the panel on all sides, a silver Dell logo in the middle at the bottom and a silver coloured stand and black base. In the bottom right hand corner of the screen is the power button which glows a nice blue colour during operation. When the screen goes in to standby, the button glows and pulses in an orange colour.

On the U2410 and U2711 models above the power button are some 'invisible' touch sensitive OSD menu buttons which glow when you hover your finger near to them. On the U2311H these are actual 'press' buttons and do not glow a colour. They look like slightly cheaper imitations of the buttons on the other models, presumably a cost cutting exercise. They have a sturdy 'click' to them and function fine.


Above: OSD menu quick launch (left) and quick access to preset menu (right).

The OSD menu buttons are not labelled in any way. Pressing any of the buttons brings up the menu in the bottom right hand corner where there are indicators on the screen itself telling you what each button does. It was easy to use and navigate, and very intuitive. There was quick access (once you've pressed the main menu button) to the preset modes and brightness and contrast controls.

The OSD menu has all the usual options you would expect. The Dynamic contrast ratio control is located in the 'brightness/contrast' section but is only available when using the 'game' preset mode.

The preset modes are available either through the quick access section, or in the main OSD menu as shown above. As you can see there are preset colour modes for a range of uses, including a 'custom' mode which allows you independent access and control of the RGB channels.

The stand offers a decent range of ergonomic adjustments, with a height, tilt, pivot and rotate function available. Dell have always done a good job in their top end monitor range of including all these adjustments, and it was pleasing to see them all available here. Height adjustment was smooth and easy but the pivot function was very stiff. You have to hold onto the base in order to re-align the screen at an angle. The tilt was smoother and easy enough to use, but the rotate was again quite stiff. There was a bit of a wobble to the screen as well, but only if you knock it. The build quality felt good and the materials were of a high standard.


Above: Side view of the screen, showing USB ports x2 on the left

On the left hand edge of the screen there was also an integrated 2-port USB hub which is always useful. There was no detectable noise from the screen and it remained fairly cool during operation as well. I tested the screen at various brightness settings and there was no issue here. It should be noted also that the U2311H is a bit thinner in profile than the U2410.

The screen uses 33W power during normal operation according to the Dell spec which has been verified by our friends at Flatpanelshd.com. In standby the screen uses <1W. The panel itself features a matte anti-reflective coating which is very similar to the U2410.

The underside of the back of the screen offers a pretty decent range of interface options. There's a single DVI-D and D-sub interface, along with DisplayPort which is fast becoming a popular connection type. There's also a further 2x USB ports (along with the upstream port to connect the screen to the PC). The screen is missing some of the further connections that the U2410 featured, like a second DVI, component and composite. Perhaps the one which is missed the most is the HDMI connection which is widely used for external DVD / Blu-ray players and games consoles. There is a connection also for the Dell Soundbar which is available separately.


Colour Accuracy, Black Depth and Contrast

Updated Feb 2011: The Dell U2311H utilises an e-IPS panel, capable of producing 16.7 million colours. The panel itself actually uses a 6-bit colour depth with advanced frame rate control (A-FRC) to produce the 16.7m colours. This is different to regular 8-bit IPS matrices, but this is likely a measure taken to achieve a lower price point for these so-called e-IPS displays. Originally the panel was listed as true 8-bit based on the manufacturers spec, but studying detailed information from LG.Display's datasheet confirms the panel is in fact 6-bit+AFRC. This review has been updated accordingly in this section.

Unlike many modern displays, the screen uses standard CCFL backlighting and offers a colour gamut covering 72% of the NTSC colour space, approximately the same as the sRGB space. For those who are wary of extended gamuts and only want to work with sRGB content, this is an important thing to note.

An important thing to consider for most users is how a screen will perform out of the box and with some basic manual adjustments. Since most users won't have access to hardware colorimeter tools, it is important to understand how the screen is going to perform in terms of colour accuracy for the average user. I restored my graphics card to default settings and set it to its standard profile. The U2311H was tested at default factory settings using the DVI interface, and analysed using LaCie's Blue Eye Pro colorimeter and their accompanying software suite.

Default settings of the screen were as follows:

Monitor OSD Option

Default Settings

Brightness

75

Contrast

75

Preset Mode

Standard


Dell U2311H - Default Factory Settings

 

Default Settings

Luminance (cd/m2)

199

Black Point (cd/m2)

0.20

Contrast Ratio

995:1

Default settings of the screen produced fairly pleasing results really. Apart from the high luminance, the factory performance of the panel was quite good. On the left we have a CIE diagram with triangles representing the colour space (gamut) displayed by the monitor. The black triangle represents the gamut of the screen itself, with an orange triangle being shown as a reference to the sRGB colour space. As you can see, the monitors colour space matches this very closely and is in keeping with other modern standard gamut displays.

Below this you will see the results recorded for gamma, which is 2.3 on average. This leaves it close to the target gamma of 2.2 which is the recommended gamma for computer monitors. Colour temperature (white point) was recorded at 6252k, being very close (4% deviation) to the target of 6500k - the temperature of daylight. As you can see, luminance was recorded at a high level of 199 cd/m2 which is considerably out from our target of 120 cd/m2, the recommended luminance for LCD screens in normal lighting conditions. At a luminance of 120 cd/m2 black point was recorded at a very decent 0.20 cd/m2, giving an excellent static contrast ratio of 995:1. Pretty much spot on to the specified 1000:1.

Testing with the colorimeter revealed the graph on the right hand side above, showing DeltaE (dE 94) values across 16 shades. As a reminder, the lower these bars down the Y-axis, the better, in terms of colour accuracy. For reference, LaCie describe the DeltaE readings as:

  • If DeltaE >3, the color displayed is significantly different from the theoretical one, meaning that the difference will be perceptible to the viewer.

  • If DeltaE <2, LaCie considers the calibration a success; there remains a slight difference, but it is barely undetectable.

  • If DeltaE < 1, the color fidelity is excellent.

Default settings returned an average dE of 2.4  which offers you fairly accurate colours even out of the box and without calibration. In some cases, the dE ranges up to a maximum of 5.6, but overall the colours were pretty even. Apart from the luminance, the screen did feel comfortable to use, with vivid and even colours. Calibration should help return even better results of course but if you don't have access to a colorimeter, the U2311H is still capable of offering you decent colour accuracy, colour temp and gamma out of the box. A simple reduction in the screens brightness control down to about 25 - 30% should return a comfortable luminance as well. Changing into the 'custom (RGB)' preset mode didn't really provide any improvements compared with the standard preset without further calibration.
 


Dell U2311H - Calibrated Settings - Custom (RGB) Mode

Monitor OSD Option

Adjusted Setting

Brightness

31

Contrast

75

RGB

87, 100, 93

Preset Mode

Custom (RGB)

 

Calibrated Settings, Custom RGB Mode

luminance (cd/m2)

120

Black Point (cd/m2)

0.14

Contrast Ratio

857:1

Entering the 'custom (RGB)' mode gives access to the individual controls for red, green and blue. I carried out the calibration process from there, using the OSD settings shown above and then allowing the automated stages to carry out further adjustments and corrections at a graphics card LUT level, and creating an ICC profile. There is no hardware level calibration possible since that is reserved for high end graphics screens.

Gamma was corrected now from default 2.3 down to 2.2. Colour temperature was now 6504k, pretty much spot on with our target. Luminance was now recorded at 120 cd/m2, being spot on with our target and a far more comfortable level for prolonged use compared with default settings. Black point was now 0.14 cd/m2, giving us an excellent calibrated static contrast ratio of 857:1. There was also an impressive correction in colour accuracy. dE was now a very low 0.2 average, with maximum of only 0.6. This was a very pleasing and excellent result, and LaCie would consider colour fidelity to be excellent. All in all, an excellent result from the screen.

Testing the screen with various colour gradients revealed no issues with banding and smooth gradients across the range. There was some very slight gradation detectable in the darker shades as common with most screen. You can use our OSD settings and try our calibrated ICC profile if you wish, which is available in our ICC profile database.

 


Dell U2311H - Calibrated Settings - Standard Mode

Monitor OSD Option

Adjusted Setting

Brightness

31

Contrast

75

RGB

n/a

Preset Mode

Standard

 

Calibrated Settings, Standard Mode

luminance (cd/m2)

116

Black Point (cd/m2)

0.13

Contrast Ratio

892:1

Out of interest I also calibrated the screen while in the 'standard' preset mode. You do not have access to the RGB controls in this mode, so apart from the brightness adjustment, all corrections would have to be carried out at the graphics card level. The obvious and rather disappointing difference here was that colour accuracy was pretty poor considering it had just been through a calibration. I tried several times to correct this, but could not get results any better than the above. dE average was 1.3 which is not bad, but nowhere near as good as the calibrated custom mode. dE ranged up to 4.2 maximum as well, still leaving significant differences between the colour requested and the colour rendered in reds and blues. I'd suggest using the custom mode for optimum results.

 

Calibration Performance Comparisons

 



 

I plotted the  results of the U2311H against other competing and popular models in this kind of size range. Out of the box colour accuracy was actually some of the best we have seen with an average dE of 2.4. This was a fair way ahead of some of the wide gamut screens we have tested like the Dell U2410 (6.7) and U2711 (3.7). It was pretty comparable to the HP ZR24W (2.5) and even the colour orientated NEC 2490WUXi (2.3), both of which are standard gamut screens. The NEC EA231WMi uses the same e-IPS panel as the U2311H and with a default average dE of 2.7, it was very comparable.

 

Once calibrated, the Dell U2311H offered some of the best colour accuracy we have seen. Average dE was 0.2, rivalling the U2410, HP ZR24W, NEC EA231WMIi and even the NEC 2490WUXi and NEC PA241W. Of course the latter two NEC models are professional grade screens which offer further technology to improve performance in colour critical applications, so don't just rely purely on this test. With maximum dE being 0.6, it was ever so slightly behind our joint top performers in this test, those being the NEC 2490WUXi and NEC EA231WMi (both maximum dE of 0.5). This was only a very minor difference of course, and the Dell U2311H offers some excellent performance once calibrated.

 



 

The above gives a comparison of black depth and contrast ratio once calibrated. The Dell U2311H offers the joint best calibrated black depth that we have seen, matching the S-PVA based 22" HP LP2275W even, at 0.14 cd/m2. This is an excellent result, and even puts it very slightly ahead of the NEC EA231WMi which had impressed us before (0.15). It's also a fair way ahead of its larger 24" brother, the U2410 which was recorded at 0.22 cd/m2. As a result, the U2311H offers the joint best static contrast ratio we have seen at 857:1, a very good result indeed.

 

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Contrast Stability

I wanted to see how much variance there was in the screens contrast as we adjusted the monitor setting for brightness. In theory, brightness and contrast are two independent parameters, and good contrast is a requirement regardless of the brightness adjustment. Unfortunately, such is not always the case in practice. We recorded the screens luminance and black depth at various OSD brightness settings, and calculated the contrast ratio from there. All other monitor and graphics card settings were left at default with no ICC profile or calibration active. It should be noted that we used the BasICColor calibration software here to record these, and so luminance at default settings varies a little from the LaCie Blue Eye Pro report.

OSD Brightness

Luminance
(cd/m2)

Black Point (cd/m2)

Contrast Ratio
( x:1)

100

242

0.25

970

90

211

0.23

917

80

193

0.21

918

70

178

0.19

938

60

167

0.18

927

50

154

0.16

962

40

140

0.15

935

30

127

0.13

976

20

112

0.12

933

10

97

0.10

965

0

82

0.09

907

 

 

The above results confirm that the contrast ratio remains pretty stable across the entire range of brightness adjustments, although does fluctuate a little between 907:1 and 976:1. Some other screens do demonstrate a slightly more stable contrast ratio, but there's no real issues here. The luminance range of the screen is 242 cd/m2 when at maximum brightness setting, down to 82 cd/m2 at the lowest setting. This does afford you a pretty decent range to adjust your luminance, and also allows you to easily reach a comfortable luminance of ~120 cd/m2 through OSD adjustments. The maximum luminance of 242 cd/m2 is a little off the specified maximum value of 300 cd/m2, but whether you ever really need to use the screen this bright is another question. A setting of around 20 - 30% should return you a comfortable luminance as a starting point should you want to aim for ~120 cd/m2.

 

Black point reduces as you would hope with adjustments in the brightness, since this is a direct control of the intensity of the backlight unit. Black point ranges from 0.25 cd/m2 at 100%, down to 0.09 cd/m2 at 0%. This is a very good performance and one of the best we have seen in this kind of size range! Contrast ratio is therefore around 900 - 970:1 across the range.

 

 

 


Dynamic Contrast

 

The Dell U2311H features a dynamic contrast ratio (DCR) control, which boasts a spec of 10,000:1. This is obviously a fairly big number even  when you consider the great static contrast ratio we have observed.  DCR requires the screen to be able to produce a very bright white, and a very dark black at the two ends of the control. Dynamic contrast ratio involves controlling the backlight automatically, depending on the content shown on the screen. In bright images, the backlight is increased, and in darker images, it is decreased. For this test I would use the colorimeter to record the luminance and black depths at the two extremes. Max brightness would be recorded on an all white screen once the DCR has caught up. Black depth would be recorded on an all black screen.

 

 

Calibrated Settings, Game Preset Mode

Max luminance (cd/m2)

129

Min Black Point (cd/m2)

0.13

Max Dynamic Contrast Ratio

990:1

 

As you can see, the DCR didn't seem to do a lot! This is not uncommon sadly, and we saw the same thing from the U2711 and U2410 to a degree. The DCR mode is available when you enter the game preset, although not in the movie mode oddly. When using the screen, you couldn't really spot any changes in the backlight intensity as content on the screen changed. In our test we noticed a slight improvement in contrast ratio from a static figure of 857:1 to a dynamic figure of 990:1 so it does seem to work a little. Certainly nowhere near the advertised 10,000:1!

 

To achieve that, and if you assumed the screen could reach its maximum specified brightness of 300 cd/m2 (which it cannot), you'd need to be able to get to a black point of  0.03 cd/m2 which we've already observed is not possible, even with brightness set at 0%. If this control did work properly on the screen and could accurately control the full range of adjustments, the theoretical maximum DCR would have been: 242 cd/m2 max luminance / 0.09 cd/m2 min black point =  2689:1....which is still a long way off. Don't be tricked by over the top claims of dynamic contrast ratios!

 


Viewing Angles



Above: Viewing angles shown from front and side, and  from above and below. Click for larger images

Viewing angles of the U2311H were generally very good. Being IPS based, you can expect wide fields of view in all directions, also being free from the VA off-centre contrast shift and the obvious limitations of TN Film matrices. Horizontally there was a contrast shift detectable from angles of >45°. Vertically the contrast shift was more pronounced, with a rather obvious change from above, and a slightly less obvious change from below. Nothing too serious, but I did feel it a was a little more restrictive than some other IPS panels. From a wide angle you can detect a purple tint to a black screen which can be fairly common on IPS models, but interestingly not something which was obvious on the NEC 23" equivalent.

 


Panel Uniformity

Measurements of the screens luminance were taken at 35 points across the panel on a pure white background. The measurements were taken using BasICColor's calibration software package, combined with the LaCie Blue Eye Pro colorimeter. The above uniformity diagram shows the difference, as a percentage, between the luminance recorded at each point on the screen, as compared with the reference point of a calibrated 120 cd/m2. This is the desired level of luminance for an LCD screen in normal lighting conditions, and  the below shows the variance in the luminance across the screen compared with this point. It is worth noting that panel uniformity can vary from one screen to another, and can depend on manufacturing lines, screen transport and other local factors. This is only a guide of the uniformity of the sample screen we have for review.

Uniformity of Luminance

 

The panel uniformity of the U2311H was fairly poor unfortunately. The left hand side of the screen was a little darker than the right if you look very closely at a solid colour background. In day to day use I doubt this would be a real issue, but might cause problems if you are a professional graphics user or someone who relies on uniform colours. In our test, this difference was picked up as you can see from the above image. The screen was 25 - 30% darker on the left hand side than it was in the middle, and from the target luminance of 120 cd/m2. Luminance ranged down to 92 cd/m2. in the worst cases. The right hand side of the screen was more even thankfully with deviance of only -12% towards the edges. This was a fairly similar result to the NEC EA231WMi in fact in terms of luminance uniformity. This does look to be a possible weakness of this 23" e-IPS panel. I could not detect any tinting of colour issues across the screen, something which has caused issues to some U2410 users.

 


Above: All black screen in a darkened room. Click for larger version

As usual we also tested the screen with an all black image and in a darkened room. A camera was used to capture the result. There was no sign of any real backlight leakage or bleeding which was a pleasing result. We'd seen some fairly obvious bleed on the NEC EA231WMi before but the Dell U2311H offered a much better result thankfully.

 


Office and Windows Use

 

The U2311H has a nice high resolution of 1920 x 1080 which is good for side by side office work. I don't think it's as practical as a 16:10 format screen with 1920 x 1200 resolution though as you do lose a bit vertically and the screen did feel smaller than a 'normal' 24" model. The aspect ratio of this screen is a pretty common trend in today's market with the move to multimedia orientated displays and widescreen formats. With a pixel pitch of 0.265mm, the text was comfortable and of a decent size for prolonged office use. Picture quality was very good using the DVI and D-sub connections, with DVI providing a slightly sharper image.

 

You will certainly want to turn down the default brightness setting for the screen as the luminance is too high out of the box. A reduction from 75% to around 20 - 30% should return a more comfortable luminance around the 120 cd/m2 mark. There's no preset mode available specifically for 'office' or 'internet' which are sometimes useful, so you will have to use perhaps the custom mode here. Some models are starting to use ambient light sensors and dynamic brightness control which I think can be useful for office use. It's not featured on this model however although the NEC EA231WMi does have one.

 

Ergonomically the screen was very good, with a decent and smooth range of tilt and height adjustments available. There's a rotate function as well in case you want to work in portrait mode. The easy access USB ports on the left hand side are useful for connecting printers, cameras etc, but it might have been nice to have a card reader as well like on the 24" U2410.

 


Responsiveness and Gaming

The Dell U2311H was tested using the chase test in PixPerAn, a good bit of software for trying to quantify differences in real terms responsiveness between monitors. As a reminder, a series of pictures are taken on the highest shutter speed and compared. The images below show the best case example on the left hand side, and the worst case example on the right hand side. This should only be used as a rough guide to comparative responsiveness but is handy as a way of keeping a constant test of each screen.

 


8ms G2G LG.Display e-IPS

 


6ms G2G LG.Display H-IPS

 


14ms LG.Display e-IPS

 


5ms G2G LG.Display e-IPS

 

The Dell U2311H has a specified 8ms G2G response time indicating the use of Response Time Compensation (RTC) technology to boost grey to grey transitions. This is actually a difference between the U2311H and the NEC EA231WMi in fact. Although both use the same panel module from LG.Display (LM230WF2), Dell have applied an RTC impulse to improve the response time, whereas NEC did not. The response time of the NEC was therefore 14ms ISO with G2G transitions likely to be slower still. When we reviewed the EA231WMi we found that pixel responsiveness was not as good as some other models and could be considered one of the weaknesses of the screen.

 

I'm pleased to say the U2311H has made some good improvements in this regard though. The panel is noticeably faster to the naked eye and you lose the blurred ghost image behind the moving car. Responsiveness is very comparable to the 24" U2410 in fact and should be more than adequate for most users. There is a slight white halo behind the moving car which you can spot in the images above, as well as to the naked eye. This is an RTC overshoot artefact and can be fairly common where RTC impulse is aggressive or not controlled perfectly. It's only minor though and not as bad as some other models can show.

 

 


8ms G2G LG.Display e-IPS

 


3ms G2G Samsung TN Film + 120Hz

 

I have also provided a comparison here between the Dell U2311H and our current champion in this test, the Samsung SM2233RZ. The super fast TN Film panel of the Samsung, along with 120Hz panel technology, can offer some marked improvements in moving images. There's very little blurring and very few RTC artefacts. The 120Hz also serves to offer a higher frame rate where needed.

 

 

The screen features hardware level aspect ratio control available via the OSD menu. However there are only options for 'fill' or '4:3' which is a little strange. You would have hoped for an option to maintain the original source aspect ratio and perhaps a 1:1 pixel mapping mode as well.

 


Input Lag

As usual I tested the screen in clone mode with a CRT to determine the level of input lag. This is something which can put off some gamers and is a delay between graphics card and monitor output. By hooking up a CRT you can show that  the LCD lags behind somewhat, which can affect users in some situations where they rely on the screen image being as fast as their inputs (e.g. fast FPS shooting games). Often, input lag is very low and probably wouldn't represent too much of a problem in real terms.

 

This test returned pleasing results. Input lag ranged from 0 - 30ms, but on average was only 10.6ms. This was a very good performance and very comparable to the HP ZR24W (10ms) we tested recently, and to the NEC EA231WMi (8.8ms) which is the U2311H's obvious competitor. The input lag was a little better than on the 24" U2410 (14.4ms) and certainly better than the 27" U2711 model (30ms). Very good performance here and this shouldn't present any real problem to even hard core gamers.

 

 


Movies and Video

The following summarises the Dell U2311H's performance in video applications:

  • 23" screen size makes it a reasonable option for an all-in-one multimedia screen, although larger screens are becoming more common place now and LCD TV sizes continue to grow

  • 16:9 aspect ratio is more suited to videos than 16:10 format screens, leaving smaller borders on DVD's and wide screen content.

  • 1920 x 1080 resolution can support true 1080 HD resolution content

  • Digital interfaces support HDCP for any encrypted and protected content

  • Fairly decent interface options available with 1x DVI (you can use HDMI > DVI if need be for digital video connection) and 1x D-sub. Also good to see DisplayPort available

  • Black depth and contrast ratio are excellent and some of the best we have seen. Detail in darker scenes should not be lost

  • Dynamic contrast ratio is available but barely works at all. Might boost the contract ratio by 100 or so from the static figure, but a shame it's not more versatile.

  • Multimedia preset mode is available. This makes the screen a little brighter and warmer compared with our calibrated custom profile. Might be a useful preset for some users.

  • Good pixel responsiveness and very low input lag meaning the screen is fine for fast moving images

  • There was no obvious backlight leakage or bleed which is good as that can become distracting when watching movies, especially where black borders are present.

  • Wide viewing angles thanks to IPS panel technology making it suitable for viewing from different positions and for multiple viewers without issue

  • Good ergonomic adjustments available as well to obtain a comfortable viewing position

  • Compatible with the Dell soundbar as an extra if you want 'integrated' speakers.

 


Head to Head Comparisons

I know people are going to ask this question, so I'll try and answer it now - "How does the U2311H compare with the other mainstream models in this size range?" I've included a little table summarising several of these screens side by side based on the testing we have carried out and on my opinions. Each screen will have either a ranking or the actual measurement shown. Where they are ranked, it is from 1st to 5th place where applicable in each category and colour coordinated:

1 - Green
2 - Yellow
3 - Light orange
4 - Dark orange
5 - Red

  • Approximate price - U2311H is the cheapest of the bunch at a very reasonable £265 GBP. This is a little cheaper even than the NEC EA231WMi which has been around for a while. It's a hefty price difference compared with the other three 24" models which is surely significant for any potential buyer?

  • Features - I've placed the U2311H as joint with the HP ZR24W but behind the other models. The U2410 and LP2475W have a wider range of interface options, things like extended internal processing (Dell U2410) etc. The NEC EA231WMi is also ranked slightly ahead as it's got an ambient light sensor and integrated speakers, so I've put that on par with the U2410 and LP2475W.

  • Interfaces - Again, the U2311H is slightly behind. There is at least DVI, VGA and DisplayPort, but no component, HDMI, composite etc as there is on the U2410 and LP2475W. The Dell U2311H has the exact same interface options as the NEC EA231WMi and HP ZR24W.

  • sRGB colour support - Obviously the U2311H has a good edge here since it's a standard gamut screen anyway. If you are wanting to work only in the sRGB colour space, the standard backlighting here is probably more suited. The NEC EA and HP ZR are also standard gamut models. The Dell U2410 does feature a fairly decent sRGB emulation mode at least, and the LP2475W's emulation doesn't seem to work at all!

  • Extended gamut support - The LP2475W and Dell U2410 are both using extended colour gamut backlighting, whereas the others are limited to only sRGB / 72% NTSC. If you want to work with extended colour spaces, the U2311H is not for you.

  • Panel Uniformity - The HP models take the combined crown here being pretty good from what we saw. The Dell U2410 has some leakage issue while the NEC EA231WMi and Dell U2311H have some fairly significant luminance uniformity issues, and in the case of the NEC - some bad backlight leakage as well. Results may vary, but this is based on the review samples we have looked at

  • Office and Windows - There's very little to separate them all here. The three 16:10 aspect screens would normally have the edge in my mind compared with a 16:9 aspect screen. However, I've bumped the NEC EA up slightly since it also offers a range of carbon saving options and an ambient light sensor which are useful. The Dell U2311H doesn't offer anything like this so has fallen slightly behind.

  • Viewing angles - only a minor separation here really, but there was a slightly more pronounced contrast shift vertically on the U2311H, ZR24W and EA231WMi than on the other two. A change relating to e-IPS vs. H-IPS here.

  • Movies Overall - I've put the U2311H slightly behind the U2410 and  LP2475W models due to its more limited connectivity which can be useful for connecting external DVD / Blu-ray players.

  • Responsiveness - They are all very close really on the most part but I'd have to give the slight edge to the U2311H. The Dell U2410 is close behind but has a slightly more pronounced trail behind the moving car. The HP LP2475W shows a fairly obvious dark RTC artefact and the ZR24W shows a slightly more noticeable ghost image. The NEC EA231WMi with it's non-overdriven panel is in last place.

  • Input lag - pretty good all round really, but the NEC EA takes the 1st place here at 8.8ms, with the HP ZR24W in a very close second at 10ms, and the U2311H very close behind it at 10.6ms. The LP2475W was perhaps the only one which was lagging (no pun intended) a little way behind the pack at 25ms.

  • Colour accuracy Default - Out of the box, the U2311H offers the most accurate colours with dE average of 2.4, closely followed by the ZR24W at 2.5. The NEC EA is also very close behind at 2.7. Neither the Dell or LP2475W offered particularly good colour accuracy at default settings or with preset modes, and need some decent calibration really to get the most out of them. This can cause further problems due to the extended gamut where over saturation of reds and greens can be common.

  • Colour accuracy calibrated - All very good and pretty much nothing in it, but the HP LP2475W falls ever so slightly behind.

  • Black depth - The U2311H holds the slight edge here over the NEC EA. There's not much in it between all these models, although the Dell U2410 does fall a little behind. The HP ZR24W is ok if you are using a 100% contrast setting (see review for details) but could be considered weak in this regard if you do not.

  • Static Contrast Ratio - as a static number of 857:1, the U2311H is the best in this test. The NEC EA isn't far behind.

  • Dynamic Contrast Ratio - The only one which really works quite well is the NEC EA at 3312:1. The Dell U2410 and HP ZR24W work to a small degree, and the U2311H barely works at all. The LP2475W doesn't feature this technology.


So as you can see, there's some tough competition in this sector. I think it's very hard for me to tell you which is the best really, since it really does depend on what you want from the screen and of course how much you're willing to spend. I would say that the U2311H is a very good screen though, and at that price, it's surely got to be a contender. Hopefully the above will help you pick out the areas which are important to you so you can decide which screen is for you.


Conclusion

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All in all I was very impressed with the U2311H. Despite it's extremely competitive price, Dell haven't really held back in features like they do on some of their more 'budget' models. There's still a decent range of ergonomic adjustments and interface options which is pleasing to see. Colour accuracy, black depth and contrast ratio are all very strong, and in fact the U2311H offers some of the best performance we have seen from any monitor in these regards. It was good to see Dell applying an RTC impulse to help boost response times compared with the NEC EA231WMi, and with input lag being very low you could easily use this screen for gaming.

 

The screen doesn't really have many weaknesses either. If I'm picky, then the ergonomic adjustments for pivot and rotate were a bit too stiff, and Dell have cut corners slightly with the loss of the touch sensitive OSD buttons and a couple of missing features. It would have perhaps been nice to see an HDMI interface and maybe even a card reader like there is on the U2410, but there's a big price difference which more than makes up for it. Luminance uniformity was fairly poor, but results may of course vary. It was at least good to see no obvious backlight leakage like we saw on the NEC equivalent which I think would pose more of an issue than luminance variations. As I've said, response time and input lag are both very good, making this a good potential gaming screen. However, oddly the hardware aspect ratio controls didn't feature a 1:1 or "aspect" mode which might have been useful to some.

 

This size range is becoming increasingly competitive with a lot of new and exciting IPS models emerging offering some very good all round performance. As long as you don't mind a slightly smaller screen (23" as opposed to 24") and  a 16:9 aspect ratio, the Dell U2311H is an amazing price and would be an excellent option to consider.

 

 

Pros

Cons

Excellent colour accuracy, black depth and contrast ratio, being strong even out of the box

Some luminance uniformity issues (may vary)

Very attractive price compared with competing models

Some slight ergonomic issues (stiff pivot and rotate)

Good responsiveness and very low input lag

Limited hardware aspect ratio control options

 

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