well....
i guess the powersupply by the motherboard(in this case gigabyte...) is on the pci/agp/pcie-sde instable...
best solution is to swap the 9600XT against a geforce 6200...
otherwise there is a iee1394(firewire) via-pci-ctrl for about 12€/$/PBD with a molex-floppy-plug, which also stabilizes the power&data-supply of the whole system, its a whole VIA8237FASTLINK - southbridge, well i had the same prob with my asus, it worked with this workaround