x8 x8 vs x16 x16

[George1]

What would be the difference (in terms of FPS) of running 2x GTX 580 cards on a motherboard at x8 x8 PCI speed as opposed to PCI x16 x16? Sorry if my phrasing is wrong, I don't really understand PCI speeds.

[BlackDwarf]

Ignore me

[scaryjim]

What resolution / settings / game?

With 2x GTX580 it's very unlikely that your frame rates will ever drop low enough for you to notice with the naked eye, tbh. And at most it'll be 1 or 2 fps difference. PCIe speed isn't really much of a limiting factor until you get down to x4 / x1.

[kalniel]

What would be the difference (in terms of FPS) of running 2x GTX 580 cards on a motherboard at x8 x8 PCI speed as opposed to PCI x16 x16?

None whatsoever.

[Pob255]

There is some but it's going to be almost nothing and not noticeable to the human eye.

With a pair of dual gpu cards it's about 5%-10% if I remember correctly. That's still the only time x16 + x16 matters.

Main thing you want to a void is missmatch motherboards where you have one slot running at x16 and the 2nd at x4 but those tend to be the cheap motherboards that don't support sli anyway.
So again it's not really an issue.

[kalniel]

There is some but it's going to be almost nothing and not noticeable to the human eye.

With a pair of dual gpu cards it's about 5%-10% if I remember correctly. That's still the only time x16 + x16 matters.

Exactly - there is no difference for a pair of single cards.

[George1]

Ok. Thanks all