ZOTAC DisplayPort to dual HDMI for multi-projector media installations

I’ve had this sitting in my suitcase for a while, finally here’s the results of trying it out: (i hope to reword some of this later when I haven’t just got off of a 12 hour flight)

This adapter belongs in the same cupboard as a Matrox DualHead2Go (part of their GXM product line) but is made by Zotac who are new to this type of device. This device being: Take 1 video output socket on your computer, plug in one of these, and get 2 outputs (in our case for 2 projectors).

When you have everything connected, the 2 outputs appear to the computer as 1 large output (e.g. if you have 2 XGA projectors attached to the Zotac, then the computer will see a 2048*768 video head attached its output). This way, you can send separate signals to the 2 projectors (the left side goes to projector 1, the right side to projector 2).

At the moment I prefer to use HDMI because:

  • Sharp, consistent signal / ‘Lossless’ (We can use the terms HDMI and DVI interchangeably when discussing signal, they’re generally the same thing but with different ends on the cable. However, HDMI can support higher frequencies whilst DVI can support dual-channel)
  • Competitive market of HDMI products (repeaters, cables, adapters. Long DVI cables are expensive whilst generally offering the same performance)
  • Decent physical connector (I find D-Sub which is used for VGA/DVI clunky and easily damaged)

Test setup

Here’s an image of the test setup:

  • ZOTAC mini DisplayPort to dual HDMI (ZT-MDP2HD)
  • Shuttle X58 XPC
  • XFX ATI 6770 Eyefinity 5 Mini-DP single slot video card (5 outs on one card for under £100!)
  • 2 x Optoma EX539 projectors (native XGA, support 120Hz)
  • 2 x 15meter HDMI straight cable

Initialisation

When you plug everything together, nothing happens. It’s only when you switch the projectors on that the computer starts to recognise that there is a display attached. In fact, if you turn on 1 projector then you get an XGA output at the computer, only when both projectors are turned on does the 2*XGA output appear in the PC settings.

This is in contrast to the Matrox which offers you the relevant resolutions directly on connection of the Matrox to the computer (the connection state of the projectors isn’t generally reported to the computer’s graphics card). This is advantageous for reliability as the state of the system from the PC’s point of view remains constant.

The behaviour of the Zotac would generally require you to turn on the projectors before turning on the PC when running an installation which starts on boot.

Supported modes

The specification quotes 2*HD is supported (3840*1080), however it was not offered to me even though the projectors support it (I’ve tested and used 1920*1080 on these projectors before on 15meter signal length). Only the native resolution was offered to the PC for the dual modes (XGA). For single head modes more resolutions were offered.

The Zotac should be able to support 120Hz XGA (XGA@120Hz ~= HD@60Hz in terms of bandwidth), but this was not supported / offered.

Selecting XGA@120Hz resulted in the signal being passed through to 1 projector only, this gives the same behaviour as an ordinary Mini-DP to DVI adapter when used with this projector.

In fact, the adapter works perfectly well as a single HDMI signal adapter. This somewhat explains the strange initialisation (it seems to switch personalities between a single and dual head adapter). Since it’s only a few more £’s than getting an active Mini-DP>DVI>HDMI adapter chain, this becomes very attractive.

Conclusion

I like it!

Advantages over Matrox:

  • Cost
    • The Zotac is £40 vs the Matrox at £100 / £150 / £250 (VGA in VGA out / VGA in – DVI or VGA out / DVI in – DVI out)
    • You save on the cost of adapters (Apple computers and ATI EyeFinity graphics cards commonly have DisplayPort sockets, projectors commonly don’t, you need adapters. For EyeFinity, DVI/HDMI adapters generally must be of the more expensive ‘active’ type).
  • Elegant
    • One small tidy device splits the signal into 2 HDMI feeds
    • Doesn’t require USB bus power
  • Signal strength
    • I generally found that the Matrox’s (tested on TH2G-Digital) can’t push DVI signal over a 15meter cable, active Mini-DP to DVI adapters generally can, this Zotac dual adapter can (in my non-noisy environment).
Disadvantages:
  • HDMI only
    • Matrox offers VGA, DVI and DisplayPort outputs (depending on model)
  • Strange initialisation
    • Could be a problem with long term installations that need to be started up every day by different people
  • Less mature
    • The Matrox devices have lots of hours clocked up, a large user base + lots of software updates
  • Only the native dual mode listed
    • It is somewhat of an advantage that it looks up the native mode and offers that, but in some situations it’s vital to send non-native signals
  • No software interface
    • If you want it!
Unknowns:
  • Supported by EyeFinity span modes? (should be equal to Matrox)
  • Can connect more than 2 of these to 1 EyeFinity card without active/passive adapter issues (should be fine)
  • Long term performance / reliability
  • Latency / motion artefacts
  • Support for all resolutions (1400*1050, 1680*1050, 1280*800, 2048*1080)

10 Responses to “ZOTAC DisplayPort to dual HDMI for multi-projector media installations”

  1. Kyle McDonald Says:

    these are the kind of analyses only you can give, elliot. keep it up! super useful. now if we can only convince zotac to find a larger distributor…

  2. elliot Says:

    I bought mine from an Amazon reseller. Shame that both this and the XFX 6770 5-MiniDP are so rare right now

  3. chris Says:

    looks interesting, i’m not convinced of the matrox stuff..

  4. I33N Says:

    Hi Elliot,
    Is it possible to plug adapters after the device? Like HDMI to DVI adapter?
    Cheers

  5. elliot Says:

    @I33N – Yes I presume this to be true since HDMI and DVI are designed to be inter-compatible without any active conversion
    i.e. they are signal-equivalent. The exceptions to this are: HDMI now supports higher frequencies, (i.e. higher resolutions than single link DVI) and DVI can come in a dual-link flavour.

    Neither of these possible differences apply here so the answer is ‘yes, you can adapt to DVI’

  6. gaz Says:

    Great post Elliot.. about time there was another option to Matrox!

  7. m4d Says:

    nice, thorough review. much obliged!

  8. Mikael Says:

    Hi. i was thinking about bying this device, if i was to set it up whit my macbook pro 13 inc, will i have the ability to have to desktops i kan work in ore will it just make a big screen on my to displays?

    By the way super rewiev

  9. uptom3 Says:

    When the specs specify 3840×1080, it means altogether, not for each monitor. So when you have the two 1920×1080 displays next to each other, it becomes one 3840×1080 display

  10. elliot Says:

    @Mikael – with your MBP 13″ you can have 2 desktops (1 is your laptop screen, the other is a 3840*1080 desktop spread across 2 external monitors)

    If you choose ‘mirror’ mode (i.e. show same on internal and external display), then you will not be able to support the dual-screen resolutions. i.e. you will output something like 1920*1080 or 1280*800 on all 3 screens, with the same desktop mirrored on all 3

    If you close your laptop, and have an external keyboard, you will get 1 desktop spread across the 2 external screens.

    @uptom3 – exactly!

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