WHQL-Certified GTX 680 Drivers Limit Sandy Bridge-E To PCI-E 2.0 Speeds (
http://www.maximumpc.com/article/ne...pci-e_20_speeds)
There is some good news, however: TechPowerUp reports that the pre-launch drivers shipped on the disc that comes with the GTX 680 enable PCI-E 3.0 on compatible Sandy Bridge-E systems. Basically, if you're a SB-E owner who feels the need for that extra data transfer speed, you can stick with the included pre-launch drivers for now and hold off on any new drivers updates until Nvidia comes up with a fix.