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Forums -> Multiple monitors -> Triple monitor setup on dual video cards.
felipey   2005-12-17 15:12
I'm buying two pci-express cards to run on a single motherboard. What would I need to do to get all three monitors working? And would I be able to play a movie across all 3 screens if I used nVidia chipset?
felipey   2005-12-17 15:42
Ok, I just read that you cant run across 3 screens, only 2. But, what would I need to do to setup an SLI setup for 3 monitors? BIOS tweakings and such.
ECarlson   2005-12-18 03:39
You're confusing the term SLI with simply having 2 PCIe video cards. When you are using 3 monitors with 2 PCIe cards, you aren't using any SLI functionality.

It might be possible to display video across all 3 monitors. It depends on the video cards and the player. If each video card supports overlay on both outputs, it should be possible to display video across all 3 monitors with the right player, and you could display the video in non-overlay mode, which would take a performance hit, but should remove any overlay limitations.

As for the specific video player and display settings you would need, hopefully someone else can answer that, or maybe you'll be able to find a combination that works, and let us know.

- Eric, www.InvisibleRobot.com
felipey   2005-12-18 03:58
But wouldn't I get better performance if I configured them as SLI? Or no?
Slackmaster K   2005-12-18 04:54
It's my understanding you can't use SLI and multiple monitors off the same cards at the same time. Or if you can, the SLI technology will only run on the primary monitor. SLI allows either card to render every other horizontal line of the video output; multiplying the number of lines by three would have an overall negative effect; even two monitors would nullify the SLI advantage. I would reccommend running one screen off the SLI system and installing a secondary dual-output card for the other two. If you have an AGP slot, I would go with the ATI Radeon 9800; it's still hella fast but for different reasons. If your AGP slot is stupidly placed between the PCIe slots (I may never figure out why they do this), you'll have to revert to a standard PCI 2.0 card. And you'll still have a sucky framerate if you manage to span your video.


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ECarlson   2005-12-19 13:48
As he said, SLI works by taking 2 video cards and driving one monitor. It doesn't do anything else, so once you go beyond one monitor on the 2 video cards, you are not using SLI, nor would there be a purpose to use SLI.

If you have 2 monitors on 2 video cards, SLI would be pointless, because you already have a whole video card dedicated to each monitor. Why would you want to dedicate half of each video card to each monitor, which is all you would be doing if you ran 2 monitors using SLI.

Maybe with 3 monitors and 2 video cards, each monitor would theoretically get 2/3 of a video card, if that was even possible, but even if it was, there would probably be some sort of performance penalty for dividing the video card's processing into odly sized pieces.

Some people, who have SLI capable systems and multiple monitors, switch between single-monitor SLI performance for gaming, then switch to regular multi-monitor mode for other stuff. Though it usually takes a reboot to switch modes.

- Eric, www.InvisibleRobot.com
Forums -> Multiple monitors -> Triple monitor setup on dual video cards.

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