SLI Using Dual PCIe 16x vs 8x - How Much Bandwidth is Needed? Linus Tech Tips
Linus Tech Tips
·Linus Tech Tips
·2011-05-08
·
462 words · ~2 min read
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today I'll be using a synthetic Benchmark in this case 3D Mark 11 to
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evaluate something that I have received
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a lot of questions about over the years
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so what you may or may not notice is that I have changed my testbench I have
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gone with an Intel x58 platform for this
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particular test I'm using the Gigabyte G1 gorilla
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motherboard's get you guys better look at that G1 gorilla motherboard with an
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Intel Cor i7 960 so that is a quad core processor
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I've got that chip clocked at 4 GHz in
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order to reduce the any CPU bottlenecks
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that may occur in my test and now okay
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no do not always ask before opening this file so what I'm going to be looking at
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today is the effect of PCI Express bandwidth on SLI performance so you can
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see I have not used the top slot and there's a very good reason for that if I
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populate the top slot then it will run at 60x bandwidth and then if I populate
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the second slot I will have two cards running at 16x bandwidth if I populate
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these two slots I will have two cards
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running at here we are PCI e16 at adex
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bandwidth so I'm just going to switch to the other card and show you guys here so
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there you are at 8X bandwidth so that is
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what we're going to test I'm going to see what the 3D Mark score is running in
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these two slots versus these two slots so you guys can see how much of a
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difference there is in performance okay so for my first run through we got X
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3386 3386 3D marks in 3D Mark 11 so now let's
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run them at 60 next and see what kind of performance boost we get from giving
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them the full available bandwidth our two card configuration running the same
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test achieves
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3,389 3D marks so for
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comparison at 8X and 8x bandwidth we
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achieved 3,386 3D
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marks so we oh oh hold on hold on no no we should put in the other one
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3389 okay divided by
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3386 to find out the performance Improvement .1
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or rather that's a
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.01% performance Improvement by going from 60 uh 8X 8X to 16x 16x PCIe 2.0
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slots so um to anyone who wants to run
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SLI or Crossfire on the Intel p67
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platform I guess this means you're pretty safe from performance degradation
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even with high performance gpus like the GTX 580 thank you for checking out this
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little episode of Linus Tech tips don't forget to subscribe for more unboxings
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