Designed for gaming use, the BenQ puts a lot of weight into its 120 Hz refresh rate. If you haven’t used a 120 Hz display before, you really need to do it in person to see the extra fluidity that it offers in comparison to 60 Hz. It isn’t something that can be captured in video, since it would be seen on a 60 Hz display, but in person it’s impossible to miss. Simple things like a mouse cursor or dragging a window are much more fluid. Playing games, animations and movement are much more fluid than with 60 Hz, and the change is almost instant to notice. Even myself, who is a casual gamer at best, can notice the difference that it makes in fluidity.

The downsides here are that all 120 Hz monitors seem to currently be limited to 1080p resolution, though some people are overdriving their import 27” IPS LCDs to do 120 Hz as well. Moving to 120 Hz at a higher resolution would also require a much more expensive graphics card, so I can understand the focus on 1080p because of that, but it also makes the monitor not as nice for general work as a higher resolution display is now.

As far as the gaming modes and the quick keys, what these modes are really doing is radically altering the gamma, going from the 2.2 that we might generally want to something closer to 1.4 in my measurements. This brings out things that might be hidden in the shadows, but in doing so it also destroys all the shadow detail and leads to a very washed out, flat looking image that isn’t attractive at all. It might offer you a bit of a performance advantage by seeing more things and not missing someone that is hidden away, but it isn’t nearly as enjoyable to look at in normal use. Perhaps if I was playing in a competitive game against someone I would utilize them, but for solo play I’m almost certain to go back to the calibrated settings, as I far and away prefer the higher contrast ratios and visual pop that it offers.

Update: Lightboost

As many people pointed out in the comments, you can use Lightboost, and some trickery, to get the XL2720T to display at 120 Hz with a strobing backlight. Working much more like a CRT, where you have black frames between objects and not object permenance on the screen, this should provide for better motion resolution and a more CRT-like feel. After I was made aware of this (it's not in the documentation with the monitor, or mentioned by BenQ, or really officially supported) and hooked the XL2720T back up and tested it in this mode.

One thing this does do it lock out all the picture controls except color and brightness. You also take a significant hit to light output in this mode. Motion does look smoother, that I can say for sure. However the extra flickering that this backlight causes also gives me a bit of a headache. I went away from CRTs to LCDs a decade ago because the flicker caused more eye-strain for me, and with the BenQ it seems to bring that feeling back. Games were smoother than before, with a noticeable difference in motion resolution, but it wasn't perfect. Losing all adjustments and the light output is a downside as well.

I also ran the numbers on the display with Lightboost enabled. As all of the controls except for Contrast are really locked off from you, then you need to rely on a video card LUT to calibrate and get anything remotely close to accurate. I also found the maximum contrast level I could drive was 48 without having severe clipping of whites. At this setting your maximum light output is 129 cd/m2. With the contrast at maximum I got 140 cd/m2 but also severe highlight clipping and color distortions.

Lightboost also causes a severe blue-shift in the image. I mean an extreme shift in the image. If you've read our display reviews, you'll know that 6503K is the ideal color temperature (CCT). Lower than that is reddish and higher is bluish. Sometimes we see a display come in around 10,000-12,000K, but that's very high. With Lightboost enabled, the BenQ has an average CCT of 36,025K. It is very, very blue. Here's a table with the data for the BenQ with Lightboost enabled, and after calibration with Lightboost on.

  Lightboost Default Lightboost Calibrated
Average CCT 36025K 6541K
Grayscale dE2000 19.8149 0.9748
Contrast Ratio 779:1 718:1
Peak Light Output 129.1 cd/m2 103.6 cd/m2
Gamma (2.2 target) 1.29 2.15
Color Points dE2000 10.6246 1.5229
Gretag Macbeth dE2000 16.7849 1.7451

So if you calibrate it, you can get a decent image with Lightboost enabled, but you also have to trade your contrast ratio and peak light output for it. It has to reduce Blue all through the video cart LUT to remove that horrible color cast on the image, and doing that drops the light output. At the default settings, the color tint is extreme and while you might be OK with it for gaming, for any daily use even those unconcerned with a calibration might find it to be way too blue for their liking. Post calibration it looks fine, though. All of the Pre- and Post-calibration charts are in the gallery below.

I wish they would make this a normal choice to use the monitor in, and not hidden away and requiring research and work. If motion resolution is the most important aspect to you, then you'll want to at least test out Lightboost mode on the XL2720T. Just know it does entail a few trade-offs as well.

For lag testing, I’ve settled on using the Leo Bodnar lag tester for reviews. Talking to other reviewers with it, our data indicates consistent results with everything except plasma TVs at this point, and that’s not an issue for PC monitors. It means I can only test 1080p60 over HDMI or DVI inputs, but that is similar to the limitations that SMTT introduced. It also lets me measure across the screen at three points and provide different data that I can then average to an overall lag number. The BenQ measures out at 22.1 ms of lag using the Leo Bodnar test. Using the FPS mode or the regular mode led to the exact same scores, so that didn’t influence it at all. I didn’t notice any perceptible lag in use, but that number is higher than I expected it to be.

Processing Lag Comparison (By FPS)

Brightness, Contrast and Power Use Conclusions
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  • althaz - Monday, June 17, 2013 - link

    What an absurd thing to say - the vast majority of people have 1080p monitors and it's not just because they represent good value for money.

    As a gamer and a worker I have a trio of 1080p monitors for several reasons:
    @ 1080p I'll be able to run games at maxed settings for a while (and I haven't upgraded for over a year).
    Dual monitor > than one big monitor (by a very long way). Triple monitor is of varying degrees of usefulness to most people, but I find two landscape and one portrait monitor is basically perfect for all tasks (some people find three monitors overwhelming however).
    Reply
  • mutantmagnet - Tuesday, June 18, 2013 - link

    We can downsample a lot of games these days. Until strobe backlighting is possible on the IPS panels settling for TN is fine since they are already cheaper and achieving 100+ FPS consistently isn't easy above 1080. Reply
  • tackle70 - Monday, June 17, 2013 - link

    Yeah I could never go back to TN panels after making the jump to IPS, and I play tons of games. I am guessing that 99.9% of gamers are not good enough for the 120 Hz to make any real difference other than as a placebo effect, and so I don't see the point.

    I wish we could get some new technologies out there other than this TN garbage :\
    Reply
  • TesseractOrion - Monday, June 17, 2013 - link

    I have a Yamasaki Catleap (IPS) and a Qnix Q2710 (PLS) , the latter at 120Hz, the former @ 60Hz (only due to DVI restriction on the 7950 GPU, had it up to 116Hz on the DL-DVI port). Hard to go back to TN and 1920x1080 now... very stripped down monitors, no scaler, OSD or multiple inputs, resulting in low input lag as compensation... Reply
  • Jedi2155 - Monday, June 17, 2013 - link

    Thanks Chris for your review. I believe it would be a better format in future reviews to add a table of specifications describing the important aspects of the product during the introduction. It took me multiple pages of skimming in order to find the information that this was in fact a standard TN panel at 1920x1080 resolution (I was hoping for a 27" IPS 120 Hz, or at least 2560x1440).

    While this information could be found with some googling, I've always come to expect AnandTech to provide very poignant and useful information very quickly and easily. Good review and I hope you will continue to refine your skills in the future!
    Reply
  • chizow - Tuesday, June 18, 2013 - link

    Questionable results and questionable competency with this review. Main concerns below:

    1) Was this monitor tested with LightBoost always enabled? Main benefit of these 3D Vision Ready panels is their ability to always be in LightBoost mode if you trick the Nvidia driver to set the 3D Vision mode to "Always On".

    2) Input lag results are questionable given this is a 120Hz input panel and the results indicate 3 frames worth of input lag. Highly doubtful on a 120Hz TN. Did you set the panel to gaming mode to see if there is a difference?

    3) I'd like to see comparisons against the Asus VG278H or even VG278HE, which have become the standard for 120Hz TN LightBoost panels.
    Reply
  • mdrejhon - Tuesday, June 18, 2013 - link

    The input lag is because the Leo Bodnar input lag tester is limited to 60Hz and HDMI. So it's not an accurate measurement of input lag. Reply
  • chizow - Tuesday, June 18, 2013 - link

    Wow, nice catch. I didn't even bother reading the testing methodology, but if true that's a pretty epic fail on reviewer's part. Not only is it probably going through the built-in video scaler/processor at that point and introducing additional latency, but it also effectively cuts refresh rate in half while doubling response times.

    Really needs to be re-done over DVI and at 120Hz with and without LightBoost.
    Reply
  • Samus - Tuesday, June 18, 2013 - link

    My last (and only) two BenQ monitors broke. I should have learned for first time after the second one caught fire. Reply
  • jigglywiggly - Tuesday, June 18, 2013 - link

    Why did you pick the worst 120hz display? Pick the vg278 or vg248qe
    both are 144hz and much better
    Reply

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