x16x16 or x8x8

[oblongsquare]

I've spent the last hour Googling this and am no better off now than I was. I've lots of stuff but it's all just people saying they are effectively the same except, maybe, on higher end cards. But there's no explanation of WHY.

I'm considering using a pair of 290x cards in Crossfire and I need to get a motherboard to support it. I can spend a ton of money getting a board that supports x16x16 or much less money and go x8x8.

I'm more concerned about the actual performance difference I'm going to see when playing FPS games like BF4. I would also like to understand what the differences are between the two configurations. Why would I want one over the other?

Thanks for any help.

 

[Sakkura]

I haven't seen a benchmark of that configuration.

However, in the past, lots of benchmarks have shown that PCIe 3.0 x8 is not a limiting factor. Whether that extends to 290X Crossfire isn't certain (due to lack of benchmarks), but highly likely.

 

[Tibbs01]

I think you will find this thread has the answers you are looking for: http://www.tomshardware.com/answers/id-1815549/motherboard-supports-dual-pcie-x16.html

 

[Sakkura]

I think you will find this thread has the answers you are looking for: http://www.tomshardware.com/answers/id-1815549/motherboard-supports-dual-pcie-x16.html

Well, that thread is from one month before the 290X launched.

 

[oblongsquare]

@Tibbs- Thanks! That thread led me to another page that really shows what's going on. http://www.techpowerup.com/reviews/Intel/Ivy_Bridge_PCI-Express_Scaling/23.html

I'm going back to read the whole article now but this answers all my questions.