X16 X4 crossfire r9 280 compatibility dilemma

[FirstTime1]

Im an absolute beginner looking at this msi motherboard: http://uk.msi.com/product/mb/Z87G41_PC_Mate.html#hero-specification

It has two Pci Express x16 slots, but one is gen3 x16 while the other is gen2 x4.

What does this mean if I want to crossfire two r9 270 cards (or maybe even two r9 290x cards)? Will one work at gen3 x16 while the other works at gen2 x4? Or will both work at gen2 x8 or gen3 x4 or something along those lines?

Will this bottleneck the graphics cards in any way, and if so, by how much?

Thanks for reading, all advice is greatly appreciated

 

[Alex Kelly]

Not sure by how much, but the x4 slot certainly will bottleneck the second card. Go for the Z87 SLI instead

 

[Novuake]

It is NOT worth it to add a second card on a x4 slot.

 

[FirstTime1]

Thanks you for your fast replies! Many people say it will bottleneck it but many also say that if it's gen3 or gen2 x4 rather than gen1 it won't matter.

https://m.youtube.com/watch?v=rSfifE2DomoZ in this video he tests x16 x8 and x4 and the difference is negligible. How very confusing!?

 

[Novuake]

You are correct that Gen3 x4 equals the same bandwidth as Gen2 X8, however as per MSIs website the x4 PCI-e slot IS ONLY X4 GEN2!

They state :

PCI-E Gen Gen3 (16), Gen2 (4)

 

[FirstTime1]

Thanks a lot. I suppose I shall choose to sell my card when it gets old and buy a new one rather than buying a more expensive motherboard, psu, and fans just to be able to crossfire in the future.

 

[Novuake]

Smart decision.