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A New 30" Contender: HP ZR30w Review

 by Brian Klug on June 1, 2010 6:30 PM EST
95 Comments | Add A Comment
95 Comments

Display Lag and Response Time

For gamers, display lag is a very real concern, and display processing is a nebulously reported (if at all) specification for just about all LCD displays. We’ve been over this before, but ultimately, what matters isn’t GTG, full on, full off pixel response times, or what’s reported on the spec sheet, but the holistic latency of the monitor compared to something we can all agree is lag-free. We previously used a baseline LCD and compared with it as our benchmark of no display lag. Previously we were using a 17” Princeton CRT - some of you were a bit underwhelmed by that monitor.

I spent some time visiting (I kid you not) almost every thrift store in town, and found myself a veritable cornucopia of uh... lovingly cared for CRTs to choose from. I settled on a much more modern looking Sony G520 20” CRT supporting a higher resolution and refresh rate. It’s still not what I’m ultimately looking for, but it’s better. Oh, and it cost a whopping $9. ;)

I had to take another trip back in time to get this CRT... Well, almost.
 
To do these tests, we connect the CRT up to a DVI to VGA adapter on our test computer’s ATI Radeon HD5870, and the LCD panel under test to DVI using an HDMI to DVI cable. I debated for some time the merits of using the same VGA signal, however, what really matters here is how the two display methods matter in the way that you, readers, are most likely to set things up. In addition, using the VGA input on any LCD is bound to add additional lag, as this is definitely a hardware scaler operation to go from analog to digital signaling, compared to the entirely digital DVI datapath. The most optimal resolution common to the LCD and CRT was 1280x800.
 
We use the same 3Dmark03 Wings of Fury benchmark on constant loop, take a bunch of photos with a fast camera (in this case, a Nikon D80 with a 17-50mm F/2.8) with wide open aperture for fast shutter speeds, in this case up to 1/800 of a second. Any differences on the demo clock will be our processing lag, and we’ll still get a good feel for how much pixel response lag there is on the LCD.

As I mentioned earlier, the only downside is that this means our old data is no longer a valid reference.

To compute the processing lag, I do two things. First, I watch for differences in the clock between the CRT and LCD, noting these whenever they are visible. I did this for 10 captures of the same sequence. Second, one can compute the processing difference by taking into account the FPS and the frame number difference.
 
 
Of course, not every one of those frames is written to the display, but we can still glean how much time difference there is between these respective frames with much more precision than from averaging the time, which only reports down to 1/100ths of a second.

Traditionally IPS panels are a bit slower (for whatever reason) than cheaper TN panels when it comes to refresh rate and processing lag. In this case, the ZR30w is a bit slower, but only by a few milliseconds, not the tens of milliseconds or perceptible lag that we’ve seen in the past. This is intriguing, it’s entirely possible HP’s omission of an OSD IC does make a difference.

We’re still evolving what we think the best way to measure processing lag is, and even using a CRT isn’t foolproof. In this case, I set the LCD and CRT refresh rates to 60 Hz so both in theory grab the same frame from the GPU’s framebuffer. In practice, it’s likely that they just aren’t, explaining the difference. As we process more LCDs, we’ll be able to tell, but the processing lag we’ve measured from all three monitors this far is totally acceptable.

I played a number of FPS titles and RTS games on the display, and never noticed any display processing lag or ghosting to speak of. If you’re going to use a 30” panel for gaming, the ZR30w seems to be just as good as any.
 
One trailing frame visible
 
LCD response and latency performance still isn’t technically at parity with CRTs, but you’d be hard pressed to tell the difference.

In the ghosting images I snapped, I usually only saw two frames. The dominant frame, and the preceding frame. This is very surprising, since we’re used to seeing three. But all throughout the images I snapped, only two frames are visible. This is very impressive panel response.
 
Analysis: Brightness Uniformity Analysis: Power Consumption
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  • MamiyaOtaru - Wednesday, June 2, 2010 - link

    are they always s-ips? I love my lp2065, but I had to find one that was advertised specifically as s-ips since not all of them were D:

  • Teemax - Wednesday, June 2, 2010 - link

    Excellent review! I appreciate the efforts in measuring the input lag!

    Looks like my Dell 3007WFP finally has a worthy replacement.

  • Mr Perfect - Wednesday, June 2, 2010 - link

    Yes, I'm glad to see it compared to a CRT rather then a "good enough" LCD with unknown input lag.

  • Earballs - Wednesday, June 2, 2010 - link

    I guess I have to assume it's 60Hz?

  • Earballs - Wednesday, June 2, 2010 - link

    redacted.

  • melgross - Wednesday, June 2, 2010 - link

    I've given up on the idea of moving to 30" from 24". I use my monitors mostly for Photoshop, video editing, publishing, etc. I've found that even IPS displays of various types show a change in brightness and contrast in the sides from sitting at the distance required for this work. Because of the large size, you're always looking at the edges at an angle that will make the difference noticeable.

    I've been looking at the new 27" displays for that reason. Apple's new 27" iMac doesn't have as much of a problem because of the slightly smaller size, but with the LED backlighting, they only claim an sRGB gamut. It's pretty good, but not for what I need.

    Is the NEC on your to do list? I hope so. The Dell 2711 hasn't proven to be all that great.

  • omf - Wednesday, June 2, 2010 - link

    Thanks for the detailed review! It seems rare to get good, technical data in reviews these days...

    I'm surprised you haven't included tests for the Dell 3008 display, though. I've heard mixed things about it and would love to see some test results.

    Thanks again!

  • R4F43LZiN - Wednesday, June 2, 2010 - link

    I would like to see a full "how to calibrate your display" one of those days here on AT. I mean, there are a few of those on the internet, but none with the kind of detail and technical aspects that we've come to expect from a AT article.

  • MauveCloud - Wednesday, June 2, 2010 - link

    "Considering other 30” displays include a plethora of input options"

    From my research of 2560x1600 monitors, only the Gateway XHD3000 (which I use now, though I had to get it repaired a couple of weeks ago - I did the research on possible replacements) and the Dell 3008WFP have component inputs, or are you referring to 30 inch televisions, with native resolution 1920x1080, rather than 2560x1600?.

    "The ZR30w has no OSD. If you recall, neither did its predecessor, the HP LP3065. At that time, HP claimed there were no ICs that could drive an OSD at native 2560x1600 resolution. Apparently this is still the case."

    My Gateway XHD3000 has an OSD at 2560x1600 (albeit not fullscreen), and so does the Dell UltraSharp 3008WFP.

  • phoible_123 - Wednesday, June 2, 2010 - link

    I've used this cable to connect a macbook pro to my 23" NEC monitor with Displayport:

    http://www.buy.com/prod/mini-displayport-to-displa...

    It actually transmits sound as well if the monitor has an integrated speaker.
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