Dell U2711 Lag and Response Time

Some users are very concerned with display lag and pixel response time. For others, they really don't notice anything unless a particular display is very sluggish. I fall into the latter camp, though I do notice the processing lag when it's above ~40ms (e.g. on the Dell 2408WFP and LaCie 324, my mouse input just felt off.) To test for display lag, we run the Wings of Fury benchmark in 3DMark03, with the output set to the native LCD resolution - in this case 2560x1440. We clone the output to our reference LCD, an HP LP3065, snap a bunch of pictures, toss out any where the time readout isn't clear, and then average the remaining results (at least 10, and usually 20 or more).

As a reminder, the reference HP LP3065 is one of the best LCDs we currently possess in terms of not having display lag. (The lack of a built-in scaler probably has something to do with this.) While we know some of you would like us to compare performance to a CRT, few users have CRTs these days and all we're really interested in measuring is the relative lag. It's possible we will find an LCD that ends up with a negative result, meaning it's faster than the LP3065, but the best we have managed so far is a tie.

Processing Lag Comparison

So far, all of the S-PVA panels we have tested show a significant amount of input lag, ranging from 18ms up to 40ms. In contrast, the TN and S-IPS panels show little to no processing lag (relative to the HP LP3065). The BenQ FP241VW with an S-MVA panel performs similarly to the TN and IPS panels, with an average display lag of 2ms - not something you would actually notice compared to other LCDs. What about the new U2711?

We tested with the "Graphics" setting and Adobe RGB as well as "Video" and "Game" - we figured the latter might disable some post-processing and result in less lag. That turned out to be incorrect, as our measured lag actually went up 2ms. However, in practice the settings are pretty much tied. That means the U2711 has around one frame of lag relative to our best LCDs, but it still has a lot less lag than our worst offenders. As stated already, I didn't notice lag in using the U2711 - just like I didn't notice lag on the 2407WFP or the FPD2485W. I did notice slight lag on the Samsung 245T and some clear lag on the 2408WFP and LaCie 324, but the threshold for lag varies and you'll need to determine if 15-17ms is too much or not for you. If you've tried any TN panels and still noticed lag, we would expect every current LCD to be above your "lag threshold".


Despite what the manufacturers might advertise as their average pixel response time, we have found most of the LCDs are basically equal in this area - they all show roughly a one frame "lag", which equates to a response time of around 16ms. Some transitions are faster than others, but the above is representative of what we found in a study of numerous photos. If you look at the tail of the center plane, you can see a slight ghost image before and after the dominant frame. Some of that will come from the camera (we use a 1/120s shutter speed), but most of it comes from the LCD panel. In this case, the U2711 panel does outperform most LCDs that we've tested, where it was often possible to see at least three frames more clearly than the two slight ghosts in the above image.

Dell U2711 Color Quality Brightness, Contrast, and Power
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  • Lord 666 - Friday, January 22, 2010 - link

    Where is the application form for writers/reviewers? I'm interested Reply
  • JarredWalton - Friday, January 22, 2010 - link

    It was posted by Anand a few weeks back... here's the link; I don't know if he's still sorting through and accepting submissions, but it can't hurt to try. :)

    http://www.anandtech.com/showdoc.aspx?i=3698">http://www.anandtech.com/showdoc.aspx?i=3698
    Reply
  • ViRGE - Friday, January 22, 2010 - link

    16x9? Boo! Reply
  • Mr Perfect - Friday, January 22, 2010 - link

    Oh, hey, you're right.

    Why did Dell make this thing a 16:9? On what planet in this or any parallel universe is a 2560x1440 display more desirable then a 2560x1600 one? I can almost understand why they make 16:9 24" screens(Look it's 1080! Full HD! It must be the bestest resolution available!), but that doesn't apply here. Give us back the other 160 vertical pixels, please!
    Reply
  • Griswold - Sunday, January 24, 2010 - link

    Agreed. its a matter of marketing bullshit. 16:10 is going the way of the Dodo just because marketing monkeys like to yip-yap about "FULL HD" resolution despite inferiority in every way - its a sad, sad world.

    But its probably not Dell at fault there, but the panel maker(s) instead. You cant sell what you cant buy as a company like Dell.
    Reply
  • AnnonymousCoward - Saturday, January 23, 2010 - link

    I totally agree, and I hate 16:9. Reply
  • strikeback03 - Friday, January 22, 2010 - link

    I'm gonna guess Apple was the one that paid some LCD maker to make a 2560x1440 panel, so Dell was stuck with that. Can't be a lot of options for these panels. Reply
  • Ph0b0s - Friday, January 22, 2010 - link

    You need to explain in your reviews of high gamut displays the implications of getting one of thoes displays. Especially to your gaming audience.

    High gamut displays are not always a good thing. They are great for photo and video profesionals who use applictions that have color management (can covert to the high gamut color space). But for every other application and game where the assumption is that the display connected is a normal gamut one, the colors will be over exagerated or just wrong. The reds and greens will sear your eyes out. Now this my be ok with the other advantages of the monitor (small dot pitch, etc), but people should be given the negatives as well as the positives.

    Hopefully all apps will become color managed at somepoint and this will no longer be an issue, but until then high gamut displays are bleeding edge. I expected better from anandtech.
    Reply
  • CSMR - Friday, January 22, 2010 - link

    Agree, it should be mentioned. Technically - aside from OS and software problems - more is better. But unfortunately I don't know of any video players that are color managed even on Windows 7. Same for games I guess. This can be fixed at the OS level but I don't think Windows 7 does that with all applications.
    Presumably there is a monitor setting for sRGB so if you are using non-color-managed software you can switch to it temporarily.
    Reply
  • Ph0b0s - Friday, January 29, 2010 - link

    A lot of Wide gamut displays have an sRGB emulation mode. But a lot of them are rubbish and don't realy do a good emulation. Seems to depend on whether hardware (lut ?) has been installed in the monitor or not. Maybe this should be part of the testing during the review to see if the sRGB emulation is any good or not. Since it is an expensive display reviewd above, then maybe the sRGB emulation is being done properly on this display.... Reply

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