On this motherboard, according to the manual, the onboard Lan is shared ressources with the PCI Express slot. As in when running Modern Warfare2 Multiplayer, both Video Card on PCIE slot and Network card are 'competing' for ressources? So adding a PCI Network card would free up ressources for the Video Card?
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They aren't using the same lanes; therefore using a PCI network card will provide no performance benefits to the video card.