Can I Crossfire two 7950's on a PCI-e 20 and 3.0 ???

[Headbomb]

I want to CrossFire in the future with two 7950s.
I want to get this motherboard but it only has one PCI-e 3.0 slot but another 2.0
http://www.newegg.com/Product/Product.aspx?Item=N82E16813157298

This one is also a ASRock but has two 3.0 slots.
http://www.newegg.com/Product/Product.aspx?Item=N82E16813157293

I am not an expert at this which is why I'm here.
Will it affect performance of will it not work properly at all?

Thank you!

 

[C12Friedman]

The PCIe 3.0/2.0 combination is not uncommon. Currently, no graphics cards (I am aware of) can saturate the bandwidth of 2.0 let alone 3.0. There should be no performance issues using the two lanes. The one performance difference I see between the two boards is that the one with two PCIe 3.0 slots will run X-fire at 8x (using two slots) whereas the other will run X-Fire at 4x (using two slots) - I do not know the impact of that difference off hand.