Topic Title: 2 7770s in crossfire, can't use 3 monitors.
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Created On: 09/18/2013 03:16 AM
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 09/18/2013 03:16 AM
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Calthies4
Peon

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Joined: 09/18/2013

So I currently have 2 7770s in my computer. Crossfire bridge is connected, and crossfire seems to be working. However, I cannot use more than 2 monitors. I have 3 hooked up, 2 to one card and 1 to the other. The 2 on the "main" card turn on fine, but the third one won't get any signal. 

The interesting thing is that I can run all 3 of them when I first install the drivers just fine. When I finished installing the drivers, all 3 monitors just turned on by themselves. Once I restarted though, I can only use the ones plugged into the top card and the third monitor goes blank. 

Does anyone know how to fix this? I've tried nearly everything I can think of. I've tried detecting displays, installing one card, the drivers, then plugging the other card in, etc... None of it works after a restart. I'm quite sure both of the cards are good, as I have been using 1 for about a year now, and I just bought the other one, and have been using it by it's self for a few days with no problems.

It has to be a windows setting somewhere or a bug, because it can obviously run the 3 monitors just fine.

Thanks for looking!

 09/18/2013 10:44 AM
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Slayerx
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When you run two cards in crossfire the second cards ports shut off so your going to have to plug all three monitors into the main card.

 



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 09/18/2013 11:26 AM
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Calthies4
Peon

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First off, thanks for the answer. I guess that would explain the problems I was having.

But, seriously? You mean to tell me that I just spent $100 on another graphics card to do Crossfire, and now I have to spend at least another $30 for an Active displayport adapter so I can use 3 monitors? Even though there are 4 perfectly capable ports on the other card on the back of my computer?

I understand that you can only use 2 monitors per card unless you use a displayport monitor or an active adapter, but I figured you could bypass that by just plugging into both cards.

 

 09/18/2013 01:39 PM
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Kent@AMD
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You can bypass it by disabling CrossFire. When CrossFire is enabled, it's solely for performance. You can use 2 cards for 3 screens, but with the way that CrossFire is designed, the outputs on the secondary card have to be disabled.

When CrossFire is enabled, the memory is mirrored, so the secondary card can't do its own thing. The Primary card gives it some jobs to do (render this texture, figure out where that shadow falls, etc), and the secondary card does it, and sends it back to the first. Trying to have the secondary card do all of that, and generate output for a single monitor, would be impossible. It's just how CrossFire is designed, which is for optimal performance, not for multiple monitors.



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 09/19/2013 10:51 AM
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Slayerx
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If your into gaming then it would be worth it to spend that extra $30 on a adaptor then you can run the game across all three monitors.

if you disable CF then you'll have two 7770's with the same performance as one wich i think is a waste. But thats just me



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FX 8320// Asus Sabertooth R2.0 // HIS R9 280x //8Gb of 1866Mhz ram, H50 cooling, HX850W psu all stuffed into a NZXT Phantom case.


Was a member of AMD Processer forum since 2008. Last post count 1818.

 09/19/2013 03:22 PM
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black_zion
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Running triple monitors on dual 7770s...Yea, abysmal FPS ville ahead...AMD makes it quite clear what display options are available, so don't get mad at anyone but yourself for not reading and comprehending, and spending $100 on a second card instead of actually about $20 for an adapter, or however much money you spent on a non DisplayPort capable monitor.

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