Crossfire on these mobos?

Chimera6586

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Jan 23, 2008
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Will either of these motherboards bottleneck the true potential of 2 HD 4870's in crossfire? I'm concerned about both of the pci express 2.0's running in x16 or will one of them drop down to x8 and therefore I will take a performance hit?

P5Q Pro: http://www.asus.com/products.aspx?l1=3&l2=11&l3=709&l4=0&model=2269&modelmenu=2
P5K Premium: http://www.asus.com/products.aspx?l1=3&l2=11&l3=534&l4=0&model=1749&modelmenu=2

I'm very confused, will these boards allow my 4870's in crossfire to perform at the maximum?

Thanks