Dual GPU vs Single GPU Card

Hi Vvvorums,

I am about to buy a lovely, big computer.

I am not sure which GPU to buy for it, a Nvida GTX285 or GTX295.

The reason for asking this is that one is single GPU card and the other a Dual GPU card. Will Vvvv see the 295 as a single card?

I will be using the VideoIn Node and have read all the posts about only being able to output to a single graphics card.

Also the dual GPU cards seem to be a bit more unstable than a single gpu card. I am trying to buiold the most stable system possible.

Has any body had any dealing with either card in Vvvv?

Ok, A bit more detail.

I am setting up a system to run a full imersive dome. This computer will control 5 projectors to create the images in the dome.
Alot iof the content will be full fisheye from a Video grabber card.

The system I am intending to make will be a Core i7 940, asus p6t v2, 12GB of Corsair XMS ram. The system will have a Graphics card with a 2 Dual Link DVI outputs. Each DVI will feed a Matrox TripleHead2Go with the projectors connected to these.

I need to use one card so that we can use video input and have it project out of all the projectors.

I would like to get either a GTX295 or GTX285 graphics card. I have heard that Dual GPU cards are more unstable and could cause issues. However, running so many projectors I could do with the extra grunt provided by the GTX295.


Would Vvvv see the GTX 295 as one card so that Video textures could be handled out of both DVI ports?
Has anybody had any experience with any Dual GPU card and Vvvv?

I’m pretty sure you can’t run 2 x 3head2go from one graphics card. I know this is the case with all of nvidia’s previous dual DVI cards. I can’t find out if their new card has changed this but i pretty sure it wouldn’t have. That’s a load of pixels to run from one card.

You’d need two cards, one for each 3head2go, and two full screen renderers out of vvvv spanning the two screen from the 3head2gos. You’d also need another screen output so you can control your content somehow. Unless you did this through a MIDI input or via another computer over a network.

You won’t have a problem using captured video across the multi screens if you apply the video to a quad using the VideoTexture(EX9.texture) and out of the renderer as a DX Texture. One issue though, if you’re planning on stretching a single video capture across the five projectors you won’t have many pixels around your dome. Even if capturing HD content I think it will still look pixelated.

Hi xd,

I have tryed your suggestion with the video texture mapped to a quad. I have attached a messy prototype patch.
I have run this on my laptop with the main screen holding the patch and one render window and a projector connected to the out put with another render window.The laptop was set up as dual view out puts. The video will only run in one render window at any given time. This seems to held up by other peoples experiences.

This is why I want to run one large render window from one graphics card.

I have found examples of people running six screen gaming rigs which gave me the idea that I could use 2 3head2go’s of one graphics card.


Prototype Dome.v4p (15.4 kB)

ok. I see the problem. anyone got any solutions?

as far as i know dualhead GPU cards cannot be set to spanmode anymore! so the one renderer solution won’t be possible.

in general it’s possible to connect two triplehead2gos to one singlehead graphiccard. but i’m not sure if it runs with 6 devices, i just testet it with 4 (two on each).

I think the spanmode option was removed from the Windows Vista Drivers but not the WinXP drivers.

I would be running WinXP Pro 64.

How do you connect 2 3head2go’s to one graphics card output?

I think the spanmode option was removed from the Windows Vista >Drivers but not the WinXP drivers.
I would be running WinXP Pro 64.

GFX-Cards with two GPUs (one for each head/output of the card), e.g. NVIDIA GTX 295, can´t be set to spanmode even under WinXP.

How do you connect 2 3head2go’s to one graphics card output?

I think phl didn´t mean “connect 2 Tripleheads to one GFX-Card output” but rather: Use a card with one GPU, e.g. NVIDIA GTX 285, and connect one Triplehead to each of both outputs.

there is actually a solution to put video across dualheads, dualmodes…doesnt matter.

flash can be put as a texture accross lots of renderers. and you can use the videocamera functionality of flash to access your videograbber. i did a proof of concept a few months ago and it did work… i can’t provide files though. just google for flash videoinput examples…

@u7angel, great solution. Thanks for the tip. Like it. Like it a lot.

Thanks for all the input guys!

I’m going to Inevestigate u7angels suggestion but if not then will go with a GTX 285 Spanned across the 2 DVI outputs.

I’ll post my results if people are interested.

yeah chunk, please do. share the love

though I better update this due to my advice being wrong… not the first time i’d imagine.

It turns out you can use 2 trippleHead2gos from the only card I’ve tested it on, a Nvidia 8800 Ultra. I’d imagine this would work with most compatible cards though. Note: the only way to get this working is to power up the computer with both trippleHeads connected.

Sorry for any mis-advice.

wasnt this a case of shared memory (ex9 texture) for accesing videoin as norml texture ?

i tested it just for the heck of it.
2 triplehead2go digital are working fine with a single gtx 285. it just doesn’t seem that useful, because as nitro said once you set your renderers to fullscreen you don’t have a control monitor anymore. also framerates-wise it failed me completely.
if you really want to do it on one system, you might have to consider a second card, but then with 5 beamers you don’t have to buy a second triplehead.

of course all this doesnt affect the video issues ;)


Some of you maybe interested to know that I went for One big computer. I have 2 GTX 275’s in it, one runs the main control screen, a 22" TFT monitor.
The second has two TH2GO’s, one connected to each head. The TH2Gos are spanned in Windows to have a single resolution of 6144x768. This is driving six projectors quite happily.

Matrox.jpg (837.7 kB)