Question about PCIe 3.0

Bearmann · May 4, 2016

Why to motherboards frequently have verbiage like this:

For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot

Isn't PCIe 3.0 x4 capable of carrying a GPU without bottlenecking? Will the new Pascal GPU's require more bandwidth than current versions?

TJ Hooker · May 4, 2016

https://www.techpowerup.com/reviews/NVIDIA/GTX_980_PCI-Express_Scaling/21.html
You do lose a little bit of performance going from x16 to x4. Relative performance hit tends to be worse at higher framerates. It's not a huge deal, but you might as well 100% performance by going with the x16 slot, hence motherboards including that footnote.

Gingerbread · May 4, 2016

PCI-E 3.0 x4 is capable of delivering as much bandwidth as PCI-E 2.0 x8.
For a gpu like gtx 980, that is not enough:
http://s10.postimg.org/5h3gjg6ax/ryse_1920_1080.gif

That is one of the reasons H170/H97 boards support only Crossfire, because best they are capable of is x16+x4, and nvidia does not allow SLI on x4, only AMD.

Bearmann · May 8, 2016

Thank you both very much! Love the supplied graphs! Always wondered why Crossfire was supported and not SLI. I hate to choose a best answer. They were both great! I guess I'll have to pick TJ since he was 4 minutes quicker to to answer with those excellent graphs.

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Question about PCIe 3.0

Bearmann

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Bearmann

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