HD 7870 in crossfire PCI-E performance

intersectnr7

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Jan 25, 2013
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Hello. I am using two HD 7870 in crossfire, but I have two pci-e slots for graphics cards, one is pci-e 3.0 16x, but the other one is PCI-E 2.0 16x(4x mode). I keep reading on internet that video cards in this kind of setup, decreases video performance. So I understand that having 16x/8x or 8x/8x is better option, but it's still better having two video cards than one HD 7870 in my case, right? Or does one HD 7870 in pci-e 3.0 x16 slot performs better, than two hd 7870?

My specs
Processor: i5-3570k
Mobo: P8Z77-V LX
RAM: 4x4GB HyperX T1 1860MHz
VIDEO: 2x Sapphire HD 7870 GHz Edition
PSU: GS700
 

intersectnr7

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Jan 25, 2013
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I've noticed that GPU-Z shows that my cards are connected to PCI-E 3.0 x16 @ 16x and PCI-E 3.0 x16 @ x4, although in my mother board manual it is said that I have 1 PCI-E 3.0 x16 slot and 1 PCI-E 2.0 x16(x4) slot.

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The two cards will still perform better than one, but would do a little better with x8/x8 slots. There is a review floating around here somewhere showing the difference between slots and basically 3.0 x4 is similar to 2.0 x8. You really aren't losing a ton of performance, maybe 10%. If you want to check performance just do a quick benchmark in a game that has it with crossfire enabled/disabled to see the difference.
 

MatildaPersson

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Jan 12, 2013
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I wouldn't Crossfire 7870's.

Crossfire is much more prone to microstutter than SLI and the lower the card in the pecking order, usually the more time spent in the 99% and rendering frames, so it's choppy and less smooth feeling.

Just sayin'.
 

gguaiato

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Feb 7, 2013
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Hey intersectnr7, can i ask you something?

Im looking forward to buy a second 7870 to my pc, but my motherboard does crossfire only at x16/x4, like yours.

So.. could you post some of your games performance here?

It'd be of much help.

Thank you!
 

intersectnr7

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Jan 25, 2013
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Hey gguaiato, in my opion, don't buy second 7870, because it will give you about 10% performance increase. Just week ago, I sold my second 7870. Well, about performance. I was playing AC3, DmC, Dead Space 2 on max settings, and it just gave me 10 fps boost in FRAPS, nothing big. I suggest you to stick with one 7870 or buy different motherboardm, because x16/x4 is not the way to go. Hope this helps, despite my corrupted english lol. :pt1cable: