General Software and Sytem Fixes

How to Setup 3 or More Monitors on Windows Without Using Eyefinity

Submitted by Derwent Ready on Sunday, 10 June 2012

A Word of Warning

I have to admit some of the information in this article might be a bit out of date as I'm not sure what innovations ATI have made regarding multi-monitor support since their first batch of Eyefinity cards. I had to swear off ATI cards because while their hardware is often superior to Nvidia's their drivers have always caused me nothing but trouble. Anyway I think most of the information in this article will be useful and informative.

A Bit of Background

I am a bit of a monitor junkie. I'm currently running 4 on one computer. You might think this is too many but it fits my programming, video and animation workflows just right. I won't go into detail but it amounts to 2-3 for video and 1-2 for web, research, chat and similar, depending on what type of work I'm doing at the time.

I made the move from 1 to 2 monitors at university when I wanted a 2nd monitor to have videos playing in the background while I drew/worked/gamed. When I eventually made the move to 3 monitors about a year later, it was a bit of a shock how difficult it was, requiring 2 ATI cards. Originally I had a high power (at the time) ATI Radeon HD 3200 and I thought, given that the 3rd monitor wouldn't really be used for games or work, only a bit of browsing and similar that a lower powered (and much cheaper) ATI Radeon 2900XT would be suitable. It turned out that ATI didn't support the use of 2 graphics cards from 2 different families. It was a mess. A few months later they released a new unified driver with better support for multiple monitors and I was able to get a fairly stable 3 monitor setup that wasn't perfect but was just about usable.

A few years later ATI released the Eyefinity cards that could support up to 3 monitors from one card. This worked fairly well but unfortunately Premiere and the ATI 5850 didn't see eye to eye, causing constant performance issues and almost-always stuttering video playback.

The Nvidia Solution

What you really need to support 3 or more monitors fairly stably is 2 graphics cards from the same or similar family of cards. NVidia seem to be a bit better about cross-family support and I was able to get a working solution using a mid-range GTX 460 alongside a GTS 210, since upgraded to a GTX 450 to get a bit more performance. With a 2 card setup, even on cards that have 3 or more inputs you need to split the connections up so that you have 2 monitors per card. There are a couple of reasons for this. The first seems to have more or less been solved with the advent of Eyefinity and Nvidia's new 3 monitor supporting cards and that is that older graphics cards could only support 2 monitors each (who needed more, right?). The second reason is that DVI and HDMI run off the same timing signal and DVI dual link can only support a maximum of 2 monitors on one timing signal. What does this mean? Well quite simply. If you have 3 or more monitors running on DVI and HDMI connections (ignoring VGA for now) each card can support a maximum of 2 DVI and 0 HDMI or 1 DVI and 1 HDMI connection. We ignored VGA because VGA is an analogue signal and much lower quality than the all-digital DVI, HDMI and Displayport connections so if you want the best quality it's best to avoid VGA. Of course you could use 1 DVI and 1 HDMI on card 1 and 1 DVI and 1 VGA on the 2nd card. This is how my original 4 monitor setup was achieved but my current setup is 1 HDMI and 1 DVI on the 1st card and 1 DVI and 1 HDMI on the second card.

The Eyefinity Way

Even though Eyefinity cards are designed to support 3 (or 6) monitors at a time and are often shipped with 3-4 inputs they are still bound by the same timing signal limitations. The way to get around this on these cards is to use 2 DVI + 1 VGA, 1 DVI + 1 VGA + 1 HDMI or 1 DVI + 1 Displayport (if one of your monitors supports it) + 1 HDMI/DVI. As I understand it, the way the 6 monitor versions work is that Displayport, not having any timing signal limitations and being designed to daisychain if needed, can be used to hook up all 6 monitors at once through 6 or less Displayport connections.

In Summary

To support 3+ monitors on one Windows box you need one of several solutions:

  • 1 or 2 ATI Eyefinity cards capable of running 3 or 6 monitors combined with;
    • several Displayport monitors (and possibly the appropriate chaining adapters)
    • a maximum of 2 DVI and/or HDMI monitors per card on a 2 card setup
  • 2 Nvidia cards of the same or similar families with;
    • a maximum of 2 DVI and/or HDMI monitors per card

I hope this article was of use to you. I've tried to setup more than 2 monitors on Linux with very little success. If you like I can try and write a post on my Experimenting with Linux blog about the problems I've encountered in doing so.

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