For some reason, all Intel chipsets available today only support PCI Express 2.0 on the primary links that are used for graphics. This applies to the 4- and 5-series chipsets employing the ICH10 southbridge. While Intel claims PCI Express 2.0 support on those links, it limits throughput to PCI Express 1.1-class performance. This is naturally a problem when we start looking at the latest high-speed motherboard-down controllers.
Well be sure what you buy 🙂