Crossfire configuration accross X16 and X8 slots

danboi63

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Jun 10, 2014
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hi guys, thinking of getting the following motherboard:
B75A-G43 GAMING

i would like to run a three card crossfire setup across multiple types of PCIE slot.

it has these slots:
• 1 x PCIe 3.0 x16 slots
- PCI_E2 supports up to PCIe 3.0 x16 speed
• 1 x PCIe 2.0 x16 slot
- PCI_E4 supports up to PCIe 2.0 x4 speed
• 2 x PCIe 2.0 x1 slots
• 3 x PCI slots, support 3.3V/ 5V PCI bus Interface

i would like to run three ATI Radeon Hemlock HD 5970 X2 2GB DX11 graphics cards.

can anybody advise as to weather it would work/ which slots to use? thanks! :)
 
Solution
Google turned up MSI motherboard. I assume this is your board.
1). This only has a pair of PCIe x16 slots. This will only support a pair of cards, not 3 off them.
2). I would avoid using 5970s anyway. They are dual gpu cards and are severely underpowered. The GTX580 was it's period equivalent, a single gpu card, and much more capable. I have both, I found the GTX 580 to be more powerful and more stable, the 5970 I stopped using long ago.

pauls3743

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Google turned up MSI motherboard. I assume this is your board.
1). This only has a pair of PCIe x16 slots. This will only support a pair of cards, not 3 off them.
2). I would avoid using 5970s anyway. They are dual gpu cards and are severely underpowered. The GTX580 was it's period equivalent, a single gpu card, and much more capable. I have both, I found the GTX 580 to be more powerful and more stable, the 5970 I stopped using long ago.
 
Solution

danboi63

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Jun 10, 2014
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4,510
thats the correct board.
ok thats brilliant, as long as i know only 2 will work :)
will it make a difference if its PCI3 or PCI2?

i would prefer to stick with ATI to be honest as the only time i ever had a nvidia card it constantly crashed :L

what about running HD 7850's 2gb in crossfire? would that be more efficient than the 5970s?

thanks for your help btw! :)
 

danboi63

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Jun 10, 2014
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4,510


thats the correct board.
ok thats brilliant, as long as i know only 2 will work :)
will it make a difference if its PCI3 or PCI2?

i would prefer to stick with ATI to be honest as the only time i ever had a nvidia card it constantly crashed :L

what about running HD 7850's 2gb in crossfire? would that be more efficient than the 5970s?

thanks for your help btw! :)
 

pauls3743

Distinguished
A pair of 7850s is more powerful, as well as being more power efficient.

As to the speed of the second slot (Gen2 x4 lanes), I don't know how much this will restrict the performance of your setup but it will hold it back the second card and won't give your system the boost it deserves. I would suggest trying for another motherboard where the second slot either supports Gen3 or has x8 lanes.

Sadly I can only speculate as to how much having the second card in a Gen2 x4 slot will be throttled. I simply don't have that knowledge/experience. When I build my own systems I ensure the second slot has a minimum of x8 lanes. Also, the 5970 was the last ATi/AMD card I bought as it was so disappointing and caused me so much trouble I've stayed on the NVidia high-end ever since.