Extended Desktop Limitations

[Wasko]

Hey all,

In the future I have a gig coming up where I'll be required to output 5 or 6 displays from my computer. In the past I have had issues with a limitation on the maximum extension of my desktop (for multiple displays). I have successfully outputted from 4 projectors before, but I have found when plugging in a 5th my Window's display configuration blacks out the 5th output and won't allow it. I have read that GPU's have limitations on maximum extended desktop sizes. As far as processing power, my computer could handle several more displays with a good frame rate if the limitation was not there.

I am looking to understand more about where this extended desktop limitation is coming from, if I can configure it to work with my existing gear (something I'm missing), or what I would need to purchase to successfully connect the 6 displays. I am also curious if my Matrox Triple-Head increases the maximum extended desktop size past my computer's capabilities or just makes use of it.

I have a GTX-980 with 3 Displayport Outs and 1 HDMI out. I connect my computer monitor via a separate DVI. I have one Matrox Triple-Head. As you can see, I have sufficient outputs - but my computer will not allow any more then 4 projector outputs (plus my monitor).

Thanks !

[Zoltán]

you can configure the triplehead to appear as a triple wide display when plugged in, then you can connect 3 of your normal sized projectors to the triplehead's output.
In resolume you will see the wide display, and you can place your slices according to where you want to output your content.
here is a short example using 2 outputs of a triplehead (2x wide).

phpBB [video]

so you'd use one output for the triplehead - 3 projectors
one for the GUI,
and you have 3 outputs left, if I count right, where you can connect another 3 projectors.

[Empyfree]

Four outputs from one card is fairly normal limitation. My suggestion would be to use a Datapath device on one or more of your outputs to create the extra connections you need. They're very flexible, also expensive, but worth it!

[Wasko]

Thanks for your response!

Ravensc - I've used my triplehead many times for 2x and 3x wide resolutions. What I was not sure of was if the Triplehead increased the amount of outputs possible from my computer - or if it was reliant on the same number (4) that was possible to begin with.

Am I correct in saying that the 4 output limitation is related to the amount of display's connected and not the cumulative resolution being too high (ie: desktop extended to 11520x1080 is too much)?

If my triplehead does indeed allow further extension of my desktop - that is perfect! (Further testing required of course).

[Oaktown]

I have a GTX-980 with 3 Displayport Outs and 1 HDMI out. I connect my computer monitor via a separate DVI. I have one Matrox Triple-Head. As you can see, I have sufficient outputs - but my computer will not allow any more then 4 projector outputs (plus my monitor).

...so you'd use one output for the triplehead - 3 projectors
one for the GUI,
and you have 3 outputs left, if I count right, where you can connect another 3 projectors.

As a reminder the GTX 980 has 3 Displayports, 1 HDMI and 1 DL-DVI but you can only use 4 outputs out of the 5 ports so if you use one Matrox TH2G and 1 UI, you only have 2 left!

But I believe you could run two Matrox TH2G with GTX 980 so you could probably get a total of 1 UI + 7 projectors.

[Joris]

A graphic card has the following limitations:
- a maximum amount of ports, in the case of Nvidia, that's 4.
- a maximum resolution per port, in the case of the GTX980, that's 5120x3200
- a maximum texture size, which is 16384x16384 on most modern GPUs. This in turn translates to: don't worry about it.

When using a TripleHead or Datapath, you use up only one of your available ports. These are extenders, so they take a larger image and then use their own hardware to divide it over its multiple outputs. Since the max resolution per port of your card is well over 4K, you are able to extend a single port to four times HD on a Datapath or three times HD on a Matrox (if its firmware supports that). Your computer will see the extender as a single, larger output, in addition to the other outputs you have connected.

When using a MST hub, you can change a single into three outputs. Each of the outputs will show as an individual discrete display on your computer. It's important to remember that a MST hub does not extend your output. This means you are still limited to the maximum number of outputs your GPU supports. Adding a 3-way MST hub to an Nvidia card with a 4 port maximum, means you will only be able to use one other port on the card. The other two will be disabled. For this reason, MST hubs are better suited to add more outputs to a single output card, like laptop GPUs.

For Resolume, it makes absolutely zero difference if you are using an extender to create a bigger output, or are using multiple discrete outputs via the card itself or MST hubs. On both options, you will be able to use all the available features for slicing, masking and blending.

[Wasko]

Problem solved - thank you everyone.

[Empyfree]

Cracking response by Joris, I'm bookmarking it for future explanations to bosses/clients.