Which PCI slot: PCIE_X16/X8_1 or PCIEX4_3 x4?

[archius]

I don't know much about mobos so thought I'd ask the experts.

I have a GTX 1070 and an Asus ROG Maximus VII Hero mobo.

I know the rule of thumb is use the top PCI slot, but I'm reading through the manual to try make heads and tails of it but it's just confusing me.

So the top slot is PCIE_X16/X8_1 (which I assume should be the one I use), but the manual (p26): http:// seems to suggest using the PCIEX4_3 slot will cause it to run in x4 mode for high performance support?

TL;DR Please could someone explain to me which is the best port for a single GPU and why?

Thanks very much

 

[Mr Kagouris]

Top slot simply because it's physically closer to the CPU, hence lower CPU-PCIe link latency. The last slot in many mobos runs at x4 which Nvidia cards will not function with.

 

[archius]

Thanks!

 

[iamacow]

The card will work in 4x, just not in SLI. I do however suggest using the top slot for 16x speeds. 4x can be a big bottleneck if you are gaming on higher resolution.

 

[Mr Kagouris]

The card will work in 4x, just not in SLI. I do however suggest using the top slot for 16x speeds. 4x can be a big bottleneck if you are gaming on higher resolution.

Nvidia cards will not function if they do not detect a minimum of an x8 link. AMD cards will, but not Nvidia (which is why many non-Z mobos support CFX but not SLI).

 

[iamacow]

I'm positive they will function under 4x. Unless Nvidia changed this in the newest generation, they will work in 4x. Its true it will not work in SLI, but a single card will function.

 

[TJ Hooker]

The card will work in 4x, just not in SLI. I do however suggest using the top slot for 16x speeds. 4x can be a big bottleneck if you are gaming on higher resolution.

Nvidia cards will not function if they do not detect a minimum of an x8 link. AMD cards will, but not Nvidia (which is why many non-Z mobos support CFX but not SLI).

No, @iamacow is right, the x8 requirement only applies to SLI. A single Nvidia card can run with a x4 connection. If you want proof, check out this article where they have a GTX 980 running with a x4 connection.
https://www.techpowerup.com/reviews/NVIDIA/GTX_980_PCI-Express_Scaling/3.html