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Looking to build several systems to output to 4 monitors over DVI. I notice most of the recent Nvidia and ATI/AMD cards have dual-DVI ports. Can I simply install two of these cards to get four monitors - or are only some cards capable of running side-by-side with another? How can I tell before purchasing?

Simon.

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5 Answers 5

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As long as you get 2 video cards that each have 2 DVI outs each, you should have no problem. The Nvidia/ATI software should help you set up your 4 monitor configuration.

Also, as Dan mentions below (thanks!):

Note: If a video card has 2 outputs, 1 DVI and 1 VGA, this may not work to go to 2 monitors even if you have a VGA->DVI converter. This is because some video cards with multiple types of output are only designed to output to 1 of them at a time.

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Note: If a video card has 2 outputs, 1 DVI and 1 VGA, this will NOT work to go to 2 monitors even if you have a VGA->DVI converter. This is because these video cards with multiple types of output are only designed to output to 1 of them at a time. You specifically need a video card with 2 DVI outputs as th3dude suggests. –  Jarvin Apr 28 '10 at 15:28
    
Good note, Dan. If you don't mind, I'll add this to my answer to make it a little more prominent. –  th3dude Apr 28 '10 at 15:32
    
Brilliant. Thanks for your comments. Will get something running tomorrow and post back if I learn anything new. Cheers. –  Simon Apr 28 '10 at 15:33
    
Good luck @Simon :) If you have any other issues, please let us know! –  th3dude Apr 28 '10 at 15:34
    
Umm, sorry guys, but Dan's comment isnt always true! It might be true for his set up, but my experience says otherwise. My onboard graphics has a DVI out and a VGA out, and both work at the same time, as did the DVI and VGA outputs on my previous graphics card! Fellow 4 monitor user here –  Kurru Apr 28 '10 at 16:03

Yes, I managed to get 4 commercial LCD screens running off my system successfully!

I used a recent motherboard with 2 x PCI-Express slots, and 2 x Nvidia Geforce 250 cards, both with dual-DVI outputs. I also needed both the PCI-E power plugs coming from the power supply into the two cards. Installation was relatively easy and pain-free, and I now have 4 monitors appearing in Windows Display Control Panel, with the ability to choose different resolutions/configurations, and using the Nvidia control panel can even rotate screens 90/180/270 degrees as required. It works brilliantly!

The only remaining issue is that if any monitor cables are removed while Windows XP is running, it somehow senses that and the configuration stuffs up - Windows may disable that monitor, and it doesn't come back up automatically when the cable is reattached. Also, the order of plugging the monitors in (while in Windows) affects the numbering of the monitors. I would prefer that those monitors remained enabled even if the cable was detached momentarily (while testing our setup). Does anyone know of a way to disable that auto-sensing functionality? Or a way of ensuring that a particular DVI port is *always* monitor 1 or 2 or 3 or 4 etc.?


UPDATE: Have since found that Windows 7 is MUCH better than XP at handling multiple monitors, especially when the plugs are taken in and out at unexpected times. Win 7 usually brings them back in the same configuration while XP does not.

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I have been searching for years for a solution to this problem and have never found anything which works. I always end up powering down, leaving only the primary display connected, powering up & booting. Powering down, conecting the next monitor, powering up, booting etc. That seems to be the only way to get a consistent order. It gets even more frustrating when you have a laptop and external monitors connected to different docking stations in different locations. –  Mark Booth May 4 '10 at 12:52
    
ultramon could help with that. Never had that issue myself tho. –  Kurru May 5 '10 at 17:59

If two video cards aren't an option for you, there are lots of multi-monitor solutions out there. Matrox have been doing multi output video cards for years, meanwhile ATI's EyeFinity technology looks very interesting according to the Toms Hardware review - 6 displayport screens from a single card.

Depending on your needs, and your budget, another option is to take each of two outputs of a traditional graphics card and split each one into a pair of screens using Matrox DualHead2Go units. This has the advantage that you are not tied to a particular graphics card and can upgrade your graphics card at any time, keeping the same monitor configuration.

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Thanks Mark. Lots of good options there, and thanks for the links, will keep them for future reference. Our earlier boxes used Matrox 4-port cards but some of the cards were designed about 10 years ago, with old drivers and lacking the features of newer cards. They also had only 32mb of VRAM instead of the 512 and 1GB models on the shelves today. –  Simon May 2 '10 at 6:12
    
That Matrox card you linked to looks good, but its AU$820 instead of AU$150 for the Nvidia cards we ended up getting (AU$300 for two). I'm not sure why they cost so much. –  Simon May 2 '10 at 6:16
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To be honest, 2d capabilitie of cards haven't really changed since the Matrox Millenium, the favoured 2d card when you could only get 3d though add in cards. If you don't need 3d, 32MB should allow a virtual display of up to 8Mpix at 32bit colour depth, which is 4x 1920x1080 screens. As for the current multi-screen Matrox cards, IIRC they tend to get used in trading systems, so I think Matrox charge what they think they can get away with. *8') –  Mark Booth May 4 '10 at 12:48

2 Graphics cards with 2 DVI's should give you 4 DVI's with no bother! Just make sure they are both by NVidea [presumably fine with ATI too] or else you could get driver issues.

You can mix and match VGA and DVI outputs on the same card if your monitors supports that.

Currently have a 8200 onboard graphics outputting through HDMI and VGA and a 275GT with 2 DVI's.

Setups that have worked for me include

  1. onboard Geforce 8200 [DVI, VGA], Geforce GT275 [2 DVI]
  2. Geforce 8200 [DVI, VGA], Geforce 8800GT [DVI, VGA]
  3. Gefore 5700 PCI [2 VGA?], Geforce 8800GT [DVI, VGA]
  4. Geforce 5200 PCI [2 VGA?], Geforce 5700 Ultra [DVI, VGA??]

You gotta love having 4 monitors! :D

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The video cards are part of the solution, but you will also need to ensure that your motherboard will accommodate two video cards at a time - many seem to take just one. Also, you'll want to be sure your power supply provides enough power for two video cards, on top of everything else that is in the system.

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Thanks, good point Grant. I found my PC's power supply had 2 x PCI-Express power plugs which then went into the two graphics cards. I think you can also get little adapters which change a HDD power plug into a PCI-E plug (some graphics cards may even come with one included). –  Simon May 2 '10 at 6:10
    
Tho you can get over this problem by using a high end PCI graphics card [highest you can find] for driver compatablity –  Kurru May 5 '10 at 18:00

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