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I have a new custom built computer with the following graphics cards in it:

  • XFX Double D HD-687A-ZDFC
  • Radeon HD 6870 1GB 256-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card with Eyefinity

I would like to know if I would be able to run 4 40" tvs and 2 24' monitors if I ran two of these cards in crossfire mode.

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migrated from serverfault.com Dec 13 '12 at 23:29

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1  
Do you mean 24 inch monitors, or 24 foot monitors (as you typed)? –  Michael Hampton Dec 14 '12 at 17:24

2 Answers 2

The XFX Double D HD-687A-ZDFC has 5 outputs (2x DVI, 2x miniDisplayport, 1x HDMI) which can be used to support up to 4 displays.

XFX-AMD_HD-687A-ZDBC image from xfxforce site

To run 6 displays you would need two of these cards.

You will have to run them as normal cards, not in Crossfire mode. (If you use crossfire then only the outputs on the main card will be used. The second card is used as a calculation unit and it will not output any signal).

Which already answers your question:

I would like to know if I would be able to run 4 40" tvs and 2 24' monitors if I ran two of these cards in crossfire mode.

No, you would six outputs on a single card to use CrossFire mode.

E.g. a newer version of this card.

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These cards will run three independent displays each if the third output (and beyond if it's a four-to-six port variant) is actually DisplayPort. If your displays don't support DisplayPort you'll need to use an active, not passive, adapter.

(Crossfire is totally irrelevant here - the cards should Just Work when you install them, no Crossfire necessary. I actually think it might disable outputs, it's honestly been long enough since I tried that I forget. I'm assuming you're talking about a modern OS - note that there is not driver support for this under Windows XP in any capacity).

EDIT: It looks like this XFX SKU is a bit of a nonstandard one, but I suspect the limitations are the same. This answer should be good for most near-reference Radeons released in the last few years as well.

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Why an active adapter? I've used a passive displayport to DVI converter before in a triple monitor setup and it's worked fine. –  nhinkle Dec 14 '12 at 1:28
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@nhinkle - Existing Radeon cards specifically tend to have at least three outputs, but only two TMDS clocks, so they can't natively push three DVI or HDMI signals - that's why active conversion to DisplayPort. This should be covered on quite a few other questions. (There are a few SKUs that do some trickery to get around this, like dropping dual-link support on one output to support a third passively on some Sapphire 6770 and 7770s, or requiring identical EDID timing data across the monitors like the FirePro 2460, but this is not that common.) –  Shinrai Dec 14 '12 at 1:39
    
Interesting. I'm driving one monitor at WQHD on dual-link DVI, another at 1080p on regular DVI, and a third at 1680x1050 on a passive DP->DVI converter. –  nhinkle Dec 14 '12 at 2:28

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