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ATI Crossfire 3 monitors - what are the connector rules?

Last response: in Graphics & Displays
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July 1, 2011 5:56:56 AM

Hi there,

Firstly, in brief I have a lovley new system ( I like it anyway :)  - I7 2600k, 16Gb-1600 RAM, X68-UD7-B3, 2 x 6780 Crossfire'd, with 2 x Benq 2400PT's (19200x1080) attached. The machine is mainily for work, but I play the odd racing game so....

After tuning on Eyfinity and starting few games across 2 monitors, I thought I would pop my old 22" (1680x1050) viewsonic on as well and see how things looked with 3 screens, but I simply can not get the 3rd screen to recognise.

I have been reading the forums, and I understand that I need to have all screens connected to ONE card for Eyfinity. The cards have 2x Mini DP, 1 x HDMI, and 2 x DVI. I have also read that you need at least one screen connected a the Displayport.

So I have the 2 2400PT's connected via DVI and they run fine. I have tried connecting the 3rd screen via a HDMI to DVI and thats when I found out that you need one to be DP. So I grabbed a mini-DP to HDMI adaptor..

So now all three screens are connected - 2 x DVI and 1 x mini-DP, but the 3rd screen will not run.

Windows detects the 3rd screen (Viewsonic on mini-DP), but is automatically set to "Disconnect this display". If I try to set it to extend, it says "Unable to save display settings" (I got the same error when it was connected via HDMI)

In Catalyst under "Detect Displays" the 3rd screen is there, but it is greyed/blacked out - I guess as it is disabled...

If I try to set it to "Extend" under "Creating and Arranging Desktops" I get the message "To extend the desktop, a desktop must be disabled." and it asks me to disable one of the other two screens.

So, here I am.... asking questions. I hope someone out there has some idea's.. Do I need the first 2 screens connected to the min-DP ports? Is there a setting / trick / hack that I have to do to get three screens going? Is it perhaps the DVI -> HDMI cable -> mini-DP adaptor config? Maybe even the fact that the 3rd screen is a different res??

I do have some strait DP -> mini-DP cables coming that hopfully will get me through it ( after I ordered DP-DP by mistake not even knowing there was mini-DP for PC's - oops ) but they are over a week away and I want to get it going.. at least to see if I want to buy a 3rd 24".

If anyone has any thoughts, I would appreciate it.

Many thanks in advance.

Michael




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July 1, 2011 6:30:52 AM

eyefinity works like this, you can have 3 monitors but one HAS to be a displayport monitor. you can have eyefinity with a non displayport monitor if you use an ACTIVE displayport adapter. these are usually pretty large and require a serperate power cable (usually usb) attached to them, hence active. they are also really expensive too.

now there are some cards that will let you use eyefinity without the need of displayport, these are the FLEX cards from Sapphire. they have this technology that allows you to use three DVI monitors for eyefinity without the need for an active adaptor or displayport monitor.
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July 1, 2011 7:08:52 AM

Thanks for that.

Hmm. My 2 x 2400PT's have display port, so with the min-DP - DP cables, I think I will be ok (once they arrive) with both of those connected to the 2 x mini-DP ports and the 3rd monitor connected via DVI.

So I guess the DVI - > HDMI (cable ) -> mini-DP (passive adaptor) is still passive... oh well.. I'll have to wait :) 

Thanks again.

Michael
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July 1, 2011 5:12:13 PM

dont they all need to be the same resolution? i know on nvidia's system they do.
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July 1, 2011 6:30:07 PM

awesome. thank you for the info computernugget
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July 1, 2011 8:45:58 PM

I just bought the Sapphire 6950FLEX from newegg. FLEX means that the card is specially designed for 3 DVI inputs. They basically give you the adapter and this doesn't cost anymore than a regular 6950. Bought mine for $279 on Newegg.com. It's working so awesomely. Plus, comes with DIRT3 for free.
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July 2, 2011 12:02:00 AM

yeah they also have so slower FLEX cards, like the 6770 FLEX and the 6850 FLEX (i think it mught 6870 though) as well. they've had the flex cards for a while but i never knew the difference between those and the regular ones until i researched more on them.
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July 9, 2011 12:35:48 AM

Best answer selected by status101.
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a b C Monitor
July 9, 2011 12:21:35 PM

This topic has been closed by Mousemonkey
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