Motherboards All you need to know about running multiple GPU's in x16 x8 x4 slots and the outcome.

AlexB · 16 Dec 2011

Fingers66 said: ↑

Over 75 FPS: http://forums.bit-tech.net/showpost.php?p=2584636&postcount=3

I recalled this article, it is worth the read: http://www.tomshardware.com/reviews/radeon-geforce-stutter-crossfire,2995.html.
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That's not high res though? I have a hunch that crossfire + eyefinity just isn't good.

Pookeyhead · 16 Dec 2011

trig said: ↑

are you true gamer? lol...i wasn't talking about your post brother...it was a reply to alex and true...DAMNIT POOKEY!
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My bad.. speed reading.

AlexB · 9 Jan 2012

I've just updated my thread - nvidia win. http://forums.bit-tech.net/showthread.php?t=222088&page=5

feathers · 9 Jan 2012

true_gamer said: ↑

The truth about running Multiple GPU's at x16 lanes vs dual X16/X8 - X16/X4 - x8/x8

This setup has the first GPU @ x16 Lanes and the second GPU in x4 lanes. The out come is he is only getting a 50% increase in FPS, where he should be nearly 90% if it was in a x16/x8 situation, and 100% Scaling if it was in a x16/x16.
Dirt3 @ 1080p, Single card = 122.1702128 average fps
Dirt3 @ 1080p, CrossfireX = 182.3529412 average fps
= around 50% increase in fps.

This is where it gets more interesting, as the more bandwidth you use when running an extreme resolution. The bigger the performance hit, and in this case with a x16/x4 configuration, he is losing FPS. Now if this was in a x16/x8 configuration, he would be expecting about a 70% Scaling increase, and at x16/x16 will be 100% scaling
And the high-res bench results were quite interesting.
The single card had a lower score and average, but a (slightly) higher max fps, where as the dual cards had a slightly higher average, but lower max. They are pretty close though

The left is a single HD6970 and the right is 2x HD6970 Crossfire

Here's another example of dual GTX 580's in a x16/x8 and x16/x16 configuration.

So at x16/x8

And at x16/x16

Know what motherboard to go for, for your desire set up, as buying something cheap, and then wanting to add a second graphics card, when running 1080p resolution +. Will leave you penalised and spending more money on a motherboard to give you the extra scaling. x16 PCIe and x16 PCIe slot with 4x lanes (x16/x4) is a scaling killer, and should be avoided. A minimum would be x16/x8 if you plan on running SLI or Crossfire. But expect a average of 10% lost at 1080p and more as your resolution increases.

I will be adding more to this as time goes on...
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I don't know anyone who runs 16/8 on socket 1155 or 1156. It's dual x8 in SLI and it has been said that doesn't lose much.

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Motherboards All you need to know about running multiple GPU's in x16 x8 x4 slots and the outcome.

AlexB Web Nerd

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Motherboards All you need to know about running multiple GPU's in x16 x8 x4 slots and the outcome.

AlexB Web Nerd

Pookeyhead It's big, and it's clever.

AlexB Web Nerd

feathers Minimodder

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