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.