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3 GPU - Set Up Only 2 Crossfire?

kellhound1
By kellhound1
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It's my understanding that with CF enabled, the second GPU's display ports won't work...I must use the primary GPU's ports.  I have an old DVI monitor that I'd like to use on a separate, third GPU.  Is it possible to have 3 AMD GPU's but only CF 2 of them?  That would theoretically leave me with one GPU on which I could use the DVI port.

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https://linustechtips.com/topic/203543-3-gpu-set-up-only-2-crossfire/
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Welcome to the forum

 

Can you not just plug the monitor in to the motherboard? Or are you on AMD?

@kellhound1

 

All monitors have to plug into the first card to use the cards in CF. If you plug a monitor into a 3rd non-CF card then it will work, but just run off that single card. If you plug a monitor into the motherboard, it will run off the iGPU.

"Rawr XD"

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And why would you do that? Crossfire all of them if they are compatible

I'd love to keep all of them CF'd, but I'm running a multi monitor system.  There aren't any more ports left on my current 2-GPU CF setup.  To give a bit more info:

 

I've got 2 R9 GPU's currently in CF mode.  My primary GPU is obviously providing the links for my mutli monitor setup.  But it doesn't provide for a DVI input, and my old monitor for some strange reason won't work with a converter from DVI to HDMI or DP.  Hence, the need for a third GPU NOT CrossFire'd.

 

I appreciate all the quick feedback.  This thing has got me perplexed.

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Welcome to the forum

 

Can you not just plug the monitor in to the motherboard? Or are you on AMD?

 

 

@kellhound1

 

All monitors have to plug into the first card to use the cards in CF. If you plug a monitor into a 3rd non-CF card then it will work, but just run off that single card. If you plug a monitor into the motherboard, it will run off the iGPU.

 

I have no idea how I'd connect my DVI monitor to the motherboard directly.  I'm using an X79-UP4.

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Why not run all 3 off the first card?

I'd be in the same problem.  If I use all three in CF then the primary card won't support my DVI monitor.  My R9's have only HDMI and DP.  And my monitor for some reason won't work with a DVI to HDMI or DVI to DP converter.  It will only work via DVI (which I tested on a separate machine).  So...if I get a cheap AMD card with DVI, I'm hoping that it won't be crossfired through Catalyst.

 

I guess that's essentially my concern and question.  If I get say an R9 270 as a 3rd GPU, will Catalyst automatically force it into CF?

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my monitor for some reason won't work with a DVI to HDMI or DVI to DP converter.  It will only work via DVI (which I tested on a separate machine). 

What are your first monitors connected with? I believe on some cards, if you're running three monitors one of them needs to be on DisplayPort, whether it's a DP monitor or a DP to something adapter, since some cards share an HDMI and DVI port and only one of the DVI ports can be used at a time if HDMI is connected.

 

And yes if you get a third GPU it will not be forced into CF because 

1. CF bridge isn't connected

2. It won't be compatible anyways

 

If you're not gaming on the third monitor you don't need a 270, just get something cheap (and single slot)

"Rawr XD"

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The R9's CF over PCIe, so there's no need for a bridge.  I suppose I could get an older card that would require a bridge and that would force it out of CF mode in Catalyst??

oh sorry i didnt no that btw why not run 3 way crossfire?

l Intel Core i7 4790K @ 4.5Ghz l Asus VII Ranger ROG l MSI GTX 970 @ 1555MHz l 


PC PART PICKER

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It's my understanding that with CF enabled, the second GPU's display ports won't work...I must use the primary GPU's ports.  I have an old DVI monitor that I'd like to use on a separate, third GPU.  Is it possible to have 3 AMD GPU's but only CF 2 of them?  That would theoretically leave me with one GPU on which I could use the DVI port.

just asking what are the GPU that you got?

 

I noticed you mentioned they dont use the CrossFire bridge

 

are they 290s?

 

how many monitors are you connecting?

 

if you are aware

 

the DisplayPort is able to support up to 3 monitors from one multistream port

 

you could just buy a displayport hub and you can link up 3 monitors from the port and free up the other ports

Budget? Uses? Currency? Location? Operating System? Peripherals? Monitor? Use PCPartPicker wherever possible. 

Quote whom you're replying to, and set option to follow your topics. Or Else we can't see your reply.

 

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just asking what are the GPU that you got?

 

I noticed you mentioned they dont use the CrossFire bridge

 

are they 290s?

 

how many monitors are you connecting?

 

if you are aware

 

the DisplayPort is able to support up to 3 monitors from one multistream port

 

you could just buy a displayport hub and you can link up 3 monitors from the port and free up the other ports

Yes, I have 2 290's.  I thought about that, but it turns out my old monitor won't work if its DVI connector is jerryrigged to work with DP or HDMI.

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Yes, I have 2 290's.  I thought about that, but it turns out my old monitor won't work if its DVI connector is jerryrigged to work with DP or HDMI.

oh i see

 

have you ever though of using the onboard display output from the mobo?

Budget? Uses? Currency? Location? Operating System? Peripherals? Monitor? Use PCPartPicker wherever possible. 

Quote whom you're replying to, and set option to follow your topics. Or Else we can't see your reply.

 

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How would I do that?  I have an X79-UP4...is there a DVI output from that?

oh i was wondering if yours was a Z97 board

 

yea X79 dont have any video output

 

the cheaper option is just buy a cheap HD5450 and use it for the 3rd monitor

Budget? Uses? Currency? Location? Operating System? Peripherals? Monitor? Use PCPartPicker wherever possible. 

Quote whom you're replying to, and set option to follow your topics. Or Else we can't see your reply.

 

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