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Radeon 6970 x2 crossfire, unable to add 3rd monitor

Last response: in Graphics & Displays
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September 16, 2011 7:18:58 PM

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.
a b C Monitor
September 16, 2011 8:12:58 PM

Are you trying to do Eyefinity or just Duplicate all the monitors?

Are you using a mini-hdmi adapter?
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September 16, 2011 8:22:05 PM

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).
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September 16, 2011 8:35:18 PM

Neither of my cards have mini-HDMI output. They have 1 HDMI, 2 DVI (1 is dual link), and 2 mini-display port outputs.
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a b C Monitor
September 16, 2011 8:38:17 PM

for 3rd monitor support for Eyefinity, on of them must have a DisplayPort "said by AMD" so you're gonna need a mini-display port to HDMI/DVI which is included in the box of your GPUs
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September 16, 2011 8:40:23 PM

I think he meant mini display port and not mini hdmi.
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September 16, 2011 8:41:12 PM

YOU NEED THE CONTROL CABLE!
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a b C Monitor
September 16, 2011 8:41:57 PM

christop said:
I think he meant mini display port and not mini hdmi.

yes i guess so
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a b C Monitor
September 16, 2011 8:44:10 PM

Lol.They are the same thing aren't they?
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September 16, 2011 8:45:09 PM

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.
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a b C Monitor
September 16, 2011 8:48:35 PM

purple stank said:
Lol.They are the same thing aren't they?

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
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a b C Monitor
September 16, 2011 8:52:27 PM

Sapphire always packs their cards with goodies,even the low end models.Their should be no reason why any maker wouldn't supply you with all the cables you need when you buying a 6970.
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a b C Monitor
September 16, 2011 8:53:38 PM

purple stank said:
Sapphire always packs their cards with goodies,even the low end models.Their should be no reason why any maker wouldn't supply you with all the cables you need when you buying a 6970.

XFX doesn't do so
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a b C Monitor
September 16, 2011 9:25:26 PM

I mean your paying close to $400 for a graphics card.The least they could do is include some extra cables that they know your probably gonna use because you have a really powerful card.Cheap bastards.
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September 16, 2011 9:34:36 PM

These are saphire cards :( 
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September 16, 2011 9:58:26 PM

Interesting comment in this thread: http://www.tomshardware.com/forum/321653-33-monitor-tur... 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..
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a b C Monitor
September 16, 2011 10:06:49 PM

You need to use an active display port adapter to use a third monitor.
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a b C Monitor
September 16, 2011 10:07:06 PM

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
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September 16, 2011 10:13:04 PM

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.
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September 16, 2011 10:14:50 PM

Quote:
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.
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a b C Monitor
September 16, 2011 10:28:10 PM

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.
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September 16, 2011 11:03:53 PM

purple stank said:
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.


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
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September 17, 2011 12:47:53 AM

Did I not say that.... anyway 2 DO NOT have to be on DVI, the only rule is that 1 has to be on an active adaptor to solve the signalling issue I mentioned above. For best performance it would be advised to plug all the monitors into display ports, 1 via an active adaptor (if you do not have a monitor with built in DP decoder/DAC) ( this ensures 100% monitor timing compatibility) but not all cards offer that many display ports.
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September 19, 2011 10:23:46 PM

The 3rd monitor still won't work using an active display port configuration with either 2 DVI or 1 DVI & 1 HDMI for the other monitors. The best I can get is 2 monitors
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September 19, 2011 11:02:53 PM

you are going in CCC,desktop management,right click on either monitor and create group?
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September 19, 2011 11:21:20 PM

Is the third monitor recognised? What exactly is your setup and what adaptor are you using?
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!