The Pro/1000GT is an older, end-of-life, PCI-X board for PCI-X bus. The DZ77GA-70K has a PCI Express bus and the old PCI-X boards are not compatible.
You will want to choose one of the newer cards which are compatible with the PCIe standard. The following ARK page should help, as it clearly identifies which cards are current and the compatible bus architecture(s).