Windows 7: PCIe speeds x16 and x4 effects on 3d performance.

I recently ordered a Gigabyte GA-890GPA-UD3H board from a supplier. The one I wanted was out of stock, so they sent me an alternate. A Gigabyte 970A-UD3. I was told by the customer service operative that the replacement board had PCIe slots that ran at x16 and x8. When the board arrived however, it turned out that the second PCIe slot only ran at x4. My question is as both graphics cards would be running at x4, with my two Sapphire 6870s AMD Phenom II 955 and 8Gb Corsair Vengeance DDR3, would the performance by the graphics cards be reduced too severely. The system is primarily used for 3D and Gaming, so the performance of this element is particularly important. Thank you very much for any advice you may be able to offer.

I don't know which Asus board you ordered but looking at the spec for what you got seems fine, supports crossfire and AMD Phenom series CPU's.

Most Asus boards have this arrangement,
1 x PCIe 2.0 x16 (blue)
1 x PCIe 2.0 x16 (x4 mode, black)
To support the same as Gigabyte does. Personally I prefer Asus, but I don't the supplier is at odds for sending you a very nearly exact part from a different manufacturer.

My error, It was another Gigabyte board not an Asus board as I stated (op edited) I forgot to include the Gigabyte board details. The board I originaly ordered was the Gigabyte GA-890GPA-UD3H.
Sorry for any confusion. Just a case of brain fade.

If the second card is running at x4 - yes, performance will be limited.

If both cards are @ x4, performance would be even further reduced.

But that board you received should be running at x16/x4.

Either way it would be lowering your frame rate a fair bit and since it's not what you ordered, I'd ask for the right board or a replacement.

x16/x8 is fine - x16/x4 isn't

Thank you very much, that's what I needed to know.

You're welcome. Good luck with your choice.