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I'd like to use three screens. I've looked on Google and found a lot of different and contradicting answers, so I decided to post a question.

What I have now: three screens, and an NVIDIA GeForce GTX 460 with 2 DVI ports and 1 HDMI port. I think that just linking the HDMI port to another screen won't work, and I've found a lot of solutions, but I'd like to hear the best and cheapest way to get it done.

I also have an old NVIDIA GeForce 8600 GT. Could I use that to send the signal, but let the 460 GTX do any calculations? Or perhaps it's possible to let Windows/the card think the three screens are one screen, so it's only really rendering one big image that can be split somehow?

Hennes
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Valura
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    You might want to specify your operating system. Edit your question, or at least ad a tag. – CarlF Jun 19 '11 at 16:04

3 Answers3

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You need to use an additional video card to get the triple monitor setup working. Additionally, if you wanted to use SLI/Crossfire in this setup, you would have to check Nvidia's website to see if triple monitors are supported (e.g. I had 2 x 8800 GT's in SLI, and had to disable SLI to get triple monitors to work - this does work with some newer Nvidia cards however). See this page for more details.

Using two video cards in non-SLI is a completely different story, and quite possible with the 8600 GT you mentioned. My recommendation is to use your one center monitor as your "main" monitor (and have the 460 GTX be that monitor's hardware acceleration), and plug the other two monitors into the 8600 GT. That way, 3D applications that output to your main display won't take a performance hit (those running on the additional monitors will - you might want to put one of them back on the main 460 GTX if you need something else hardware accelerated).

The core requirement from Nvidia's website to use an additional video card to drive an additional monitor is:

Additional monitors (up to 6 monitors total enabled) may be enabled by using either a motherboard GPU and/or a PhysX capable graphics card (GeForce 8 series or higher with at least 256MB of memory) that does not have the same GPU as those that are SLI enabled. More information regarding multi-monitor in SLI can be found here.

The above information applies wether or not you use SLI.

Breakthrough
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  • Is there any way to not have the performance hit when using the 8600GT? I think SLI is not *really* supported here, but assuming it does, would it be possible to only let the 8600gt function as a 'bridge', where the 4600gtx would still calculate everything, and the 8600 only supplies the 3rd connection? Or would this be possible without SLI someway? – Valura Jun 19 '11 at 15:31
  • @Valura no, unfortunately this is due to issues higher then the driver-level. Windows allows the selection of a single hardware accelerated display (which is called the "focus display"). The Nvidia drivers only allow you to accelerate the displays connected to a single video card at a time. Read the second link in my answer for more details (there are a few FAQ questions with some details related to your question). – Breakthrough Jun 19 '11 at 15:36
  • Alright, so how about 'fusing' the screens? If windows and the card think that for example screen 1 and 2 are just one big screen, it would be possible to run 3 screens with only a 460gtx? Is this just a stupid idea or is it possible someway? – Valura Jun 19 '11 at 15:44
  • While it is very possible, no solution for that already exists - you would essentially need to create a discrete hardware device to further process the fused DVI signal into two separate display signals. – Breakthrough Jun 20 '11 at 02:01
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If you have on-board video-card, which almost every computer has now, since the new CPU's have a built-in graphics card on the chip...

Use that for one of your side monitors. (Since that will be one of the slower ones.) You may have to ENABLE ONBOARD VIDEO in your BIOS, if it is not seen. Some computer builders turn it off, to stop confusion, due to using external PCIe/AGP cards for video-out.

Then use the other two for the remaining monitors, from your graphics-card.

The issue with HDMI/DVI-#1/DVI-#2 on your card, may be that it was intended to be one or the other... HDMI/DVI-#2 or DVI-#1/DVI-#2, not HDMI/DVI-#1/DVI-#2

Unless it says "3-view" or "2+ monitors", etc... (I have Hydra-vision, so mine has 2 additional mini-DVI, which outputs up to 4 DVI connections per mini-DVI port. There is a special cable needed for that, which I don't have. However, I can still only use one of the mini-DVI port, if I use either HDMI or DVI for the other connections.)

Windows doesn't care what video-cards are used for output. It has direct-access to the RAM and PCIe busses, in the I3-I7 series and higher CPU's. (Which is why memory speed and bus-speeds are tied to CPU speeds. Otherwise the data doesn't align, and can't be read.)

https://www.laptopmag.com/articles/intel-hd-graphics-comparison

Whatever card you have, that is NOT the one built-in to the CPU, will be the controlling card. It just sends the "drawn images" to the other two ports. That requires almost no slow-downs, as the rendered image is low in data. Your internal CPU graphics-card will not be doing any actual processing, except spitting-out the image it was just sent, to the on-board port chip.

The on-board port may be near your USB connections. Often just below them, against the tower-case edge. That may be limited to only HDMI, or DVI, or it may have both, but only one will work. For the same reason as with the video-card... It is one or the other, not split-view. (It was done that way so you wouldn't have to buy a spotty or laggy HDMI->DVI converter, or the other way around.)

http://www.pcstats.com/articleimages/201011/ecsH67H2_d4.jpg

Your video-card software will see all three screens and give you control from those settings, for all three screens. However, that one screen, controlled by your CPU, will also have an individual set of display drivers too. Those will only control that one screen. (Used to adjust things like fit to screen, orientation, etc...)

NoesisAndNoema
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I doubt this is useful for your configuration, as this is a very old question, but I was looking for non-expensive cards which would allow me to do triple monitoring with at least one 4K monitor at 60 Hz with RGB colors and, as the info is scarce, maybe this would be of help for someone.

My desktop PC is an i7-3770 with an integrated HD Graphics 4000 with a DVI, an HDMI and a VGA output. Although not clearly stated in the specs, or misproperly stated that you need at least one DisplayPort or at least an integrated (laptop) screen for triple monitor, I get it working out-of-the-box for desktop on Linux, while I'm only able to get dual screen on Windows 7 (haven't tested on newer versions). Max. resolution is FullHD on both operating systems.

Using a GT-710 instead, with the same physical connectors, I manage to get triple monitor on both operating systems, this time even running 4K on at least one of them (but just on Windows; this time, Linux max. resolution is, again, FullHD). The drawback is that GT-710 HDMI output is only 1.4 version, thus you cannot have RGB color space at 4K 60 Hz. You need to lower your refresh rate, which leads to jerky mouse movement, or reduce chroma subsampling, which results in visual color artifacts :/.

Starting from second generation Maxwell (GM20x), it seems their HDMI output(s) is/are 2.0 compliant. Nevertheless, it looks like not every card allows triple monitor configuration, despite having 3 or more physical outputs and being newer models. So I have to find yet an acceptable solution.

Pere
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