There should be no noticeable difference in performance as 16x PCI-E 1.1 is still enough bandwidth for that card. You can only see the small difference in synthetic benchmark results but not that much. The real question is if the motherboard is fine with PCI-E 2.0 cards (early 1.0 boards were not up to standard and may need a BIOS update if it works at all) and if the CPU can keep up ^_^.