Radeon 6970 x2 crossfire, unable to add 3rd monitor

jfmorrison

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Hello,
I have 2 Radeon 6970 and the cross fire bridge. I am unable to have the 3rd display function properly. I can switch the position of the cards and the monitor outputs and they all work in dual display perfectly. Unfortunately, I am unable to get the 3rd to work. Any help is appreciated.
 

jfmorrison

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At the moment, I am just trying to get windows to recognize the 3rd monitor. I'd like to use Eyefinity for surround gaming. I am using HDMI and DVI cables but not display port or mini HDMI. When I plug the 3rd monitor in to the primary card windows makes the "device attached" sound.

FWIW the monitors are a Hanns-G HZ281HPB 27.5 and 2 ASUS VH226H 21.5. I have tried it with 3 Hanns-G HZ281HPB 27.5 (all 1080p, all iterations of DVI/HDMI).
 

jfmorrison

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I ordered mini display port to HDMI and DVI adapters. If this is a somewhat known issue I'm not happy that ATI doesn't discuss it on their website, nor do they provide the appropriate converters with the cards.
 

first of all, i have never seen a mini hdmi port in AMD GPU only wish nVidia's.... and somehow Eyefinity requires a Displayport for 3rd monitor you can discuss "why" with AMD
 

jfmorrison

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Interesting comment in this thread: http://www.tomshardware.com/forum/321653-33-monitor-turn that you can use both DVI, a DVI and an HDMI, or a DVI and a display port.

I have 2 cards installed though. I fully expect to be able to use an HDMI on each or a DVI on two, etc.

The issue, moreover, is that the 2nd card is "dead" to output and the remaining ports on the primary card are dead as well. The card is clearly recognized and I can crossfire it.. I just can't get a display from it..
 
DVI is exactly the same as HDMI but without a sound output...
your eyefinity should run as the following 1 monitor VIA regular DVI, 1 monitor VIA HDMI, 1 monitor through the DisplayPort adapter
what do you mean by dead ? if a signle output in the card not functioning you should RMA
 

Ninja Pants

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You need an ACTIVE display port to DVI cable. Your card should have included a mini DP - DP adaptor as mentioned above to enable the third monitor.

The reason is due to signalling, DVI/HDMI (VGA uses the same clock as well I think) requires a special clock which the cards only provide two of, DP uses a different clock.

Why active over passive? because; passive adapters are merely a cable to go from displayport to DVI/HDMI/VGA, Active adapters, on the other hand, receive a displayport signal from the video card, and convert it to DVI/HDMI/VGA. They include an on-board DAC or video converter with its own signal clock generator.
 

Ninja Pants

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Interesting comment in this thread: http://www.tomshardware.com/forum/ [...] nitor-turn that you can use both DVI, a DVI and an HDMI, or a DVI and a display port.

I have 2 cards installed though. I fully expect to be able to use an HDMI on each or a DVI on two, etc.

The issue, moreover, is that the 2nd card is "dead" to output and the remaining ports on the primary card are dead as well. The card is clearly recognized and I can crossfire it.. I just can't get a display from it..

All monitor must be plugged into the one (master) card.
 
I think he wants to use all the ports on each card.Sorry to say that's not how it is with AMD.You can only use the top card for display output and only certain combination.That's just how it is and how AMD chose to set it up.
It's the same wierd configuration for Nvidia Surround but you have to use 2 cards for it to work.I think like 2 DVI's in the top card and 1 DVI on the bottom or something like that.
 

Earnie

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finally someone said it
all monitors on AMD cards MUST be plugged into primary card only.2 on DVI and one using an active display port