I have two Sony Viao computers, one is 3.4mhz and the other is 3.2mhz. I wanted to upgrade them both to an x800 XL but I'm having issues. After uninstalling the old drivers and putting the new cards in, the computers don't start up properly. I hit power and can hear the computers and the cards turning on, but I don't get any picture at all on the monitors. The old video cards were an x600xt and an x300 SE. Any ideas?