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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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  • phoible_123 - Tuesday, June 1, 2010 - link

    Will this connect directly to a Macbook pro with a mini displayport -> displayport cable?

    I've been able to connect a MBP to other displayport monitors, and would like to know whether you can drive a dual-link display this way.

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

    I spent a greater part of today searching around town for a miniDP to DP adapter, but couldn't find that nor the cables. I'm under the impression that it will work, and might even pass the 10-bit deep color data too. I'm hopefully getting an adapter soon.

    Cheers,
    Brian

  • kasakka - Thursday, June 3, 2010 - link

    I have a Dell 3008WFP that I've connected to my late 2009 Macbook Pro with a mini-Displayport to Displayport cable using this cable:

    http://estore.circuitassembly.com/products/Mini-Di...

    It works perfectly and avoids the issues with the overpriced Apple mini-DP to dual link DVI adapter.

  • Brian Klug - Wednesday, June 9, 2010 - link

    Hey, just letting you know that the ZR30w does work driven from the 2010 MBP over a mini Display Port to Display Port cable. Flawlessly, really. No problems at all thus far!

    Cheers,
    Brian

  • Mishaux - Monday, May 21, 2012 - link

    Hey Brian,

    I realize this is a few years late, but I am trying to make this work with a mid 2010 15" MBP and having no luck. Did you have to do anything other than plug it in?

    Thanks!

  • Mumrik - Tuesday, June 1, 2010 - link

    Nine bucks for a G520!?!??!

    Screw LCDs :-D

  • Bolas - Tuesday, June 1, 2010 - link

    So... what's the refresh rate? 60 Hz? 75 Hz? 120 Hz? 240 Hz? I didn't see the refresh rate on the table of specifications, and that would be something worth knowing for people in the market for a high res 3D display.

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

    The refresh rate over DVI is still 60 Hz, at least as reported in the display manager.

    Cheers,
    Brian

  • GoodBytes - Tuesday, June 1, 2010 - link

    60Hz, it's always 60Hz for computer monitor using IPS or PVA panels.. well today... it might change later.

  • Bolas - Tuesday, June 1, 2010 - link

    I figured it was 60 Hz, but you'd think that they would spell that out in the specs. Pity it doesn't have pivot feature, but whatever.
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