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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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  • prof.yustas - Tuesday, June 1, 2010 - link

    Thanks for the review, but I think most people would be more interested to see a review of HP ZR24w. Are you planning to review it?

  • Brian Klug - Tuesday, June 1, 2010 - link

    Hey, yeah we're definitely working on getting the ZR 22" and 24" displays for review. I know that everyone is very excited for us to get those and start working on em - at least I know I am! Should be within the month.

    Cheers,
    Brian

  • kenyee - Tuesday, June 22, 2010 - link

    Only negative is it doesn't do 1:1 display of 1080p inputs...it scales it up to 1200 lines all the time. A bunch of ZR24W owners have filed bugs w/ HP, but no word on getting this fixed yet :-P
    If Anand could check this and gripe as well, it might help :-)

  • CSMR - Tuesday, June 1, 2010 - link

    Good review, useful data.
    I do think the input options are just right for this: DVI+displayport. This is a PC monitor so these are the right options. Devices that use hdmi (consumer electronics, smartphones etc.) generally can't output 2560x1600.

  • icrf - Tuesday, June 1, 2010 - link

    Yeah, but my personal Dell 3007 WFP-HC's DVI-D only means I can't hook up my work Dell M6400 laptop, as it has VGA and DP outputs only. I need a docking station for the two to mate, though I can't convince myself or the office that it's a worthy expense.

    More inputs is always better, even if there are downsides to the others (clarity, lag, etc).

  • softdrinkviking - Tuesday, June 1, 2010 - link

    while i agree that added connectivity is always a good thing,
    if the lack of extra inputs shaved a $100 off the price, then it's why i, and a lot of other folks will buy one.

  • GoodBytes - Tuesday, June 1, 2010 - link

    Display Port can be converted easily with an adapter to HDMI (with audio if your laptop supports audio with DP) or even DVI without any difficulties. And the adapters are fairly cheap and small.

  • erple2 - Wednesday, June 2, 2010 - link

    Does HDMI even have the bandwidth to support the native resolution? I don't think so - it's limited to at most 1920x1200.

    It therefore makes perfect sense to me to not include an HDMI connector.

  • platinum__1 - Tuesday, July 13, 2010 - link

    As of HDMI 1.3 the max resolution is 2560x1600p at a 30 bit pixel depth. HDMI 1.4 will do 2k and 4k over single link to a resolution of 4096x2160p at up to 36bit pixel depth. (referenced from wikipedia for concise comparison charts). That is not to say that any given HDMI output to a device, or for that matter, a display port adapter will be able to deliver it due to the individual ports build, but it is possible under the right circumstances.

  • samhall - Monday, January 9, 2012 - link

    just wondering if anyone knows how to connect an xbox up to this monitor. I have connected it by getting an addapter for the DVI-D port but cant get anything on the screen.
    Can someone help Please??????
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