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Crossfire PCI-E Question

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February 3, 2010 2:00:04 AM

I currently have one HD 4890 Sapphire Vapor-X 1GB on my M4A79 Deluxe Motherboard (PCI-E 2.0 @ dual x16, triple x16 / x8 / x8, or quad x8 link). I will be purchasing another HD 4890 soon, and a third in July. What are the cons of having 3 GPU's on my motherboard when it comes to the "link"? What does the x16 even mean? I've been doing some looking around, but I can't find the answer.
How much of a performance decrease is it with x8 instead of x16?

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February 4, 2010 1:12:42 AM
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http://www.tomshardware.com/reviews/performance-gaming-... here you'll get a glimpse of the tri fire at work and ,
http://www.tomshardware.com/reviews/pci-express-2.0,191... to understand the limitations that pci express has at x4 x8 but the test were done with an 3870 ...
hope it helps
February 4, 2010 8:39:44 PM

With 2 Cards in CF you only gain at best 30%,it may be as little as 20% so i was told when i went CF. I think to go Tri fire would be a waste of money imo,the card will not get to anywere near its potential,well your second card wont to be honest.Unless you plan on running resolutions above 1920x1200 i would not go tri.I will not go CF again,i would rather save a little more and get a better single card,at least you know that you will be using all of it.
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February 4, 2010 8:48:09 PM

andy_93 said:
With 2 Cards in CF you only gain at best 30%,it may be as little as 20% so i was told when i went CF. I think to go Tri fire would be a waste of money imo,the card will not get to anywere near its potential,well your second card wont to be honest.Unless you plan on running resolutions above 1920x1200 i would not go tri.I will not go CF again,i would rather save a little more and get a better single card,at least you know that you will be using all of it.


CF is better than "30% at best". At best, I've seen a few games with 100% scalability or strangely enough, more than 100%, but I've sen some with 0% (if CF is not supported).

Check this out for CF scaling: http://www.xbitlabs.com/articles/video/display/radeon-h...

Keep in mind, that if your CPU is holding you back, it won't scale as well, which is why the higher resolutions show higher scaling as they put more stress on the GPU in comparison to the CPU.
February 4, 2010 10:09:52 PM

http://www.tomshardware.co.uk/p55-pci-express-scaling,r...

P55 and X58 chipset motherboards have an average of 55-60% increase in performance in crossfire. Depends on the game, yes some can get to 100%.

That 30% is old information and only applys to P45, G35 and older chipsets (anything but the newer P55/X58 ect).
February 4, 2010 11:03:40 PM

That's pretty impressive scaling on the X58 system, including that tri-fire setup.
February 5, 2010 1:09:25 AM

Thank you all for the help. Especially Mobutu with the second link.
Come to think of it, I probably won't need a third HD 4890 for years since I'm playing on 1680 x 1050.
February 5, 2010 1:09:38 AM

Best answer selected by rysterf.
a b V Motherboard
February 6, 2010 2:35:52 AM

This topic has been closed by Mousemonkey
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