have a gigabyte 4650 in my machine (dell p4 at3.0) If i remember corectly the latest drivers will not work with these cards? I believe the instructions for my stated that you had to use the drivers on the disk sent with the card. Did this a while back but If I remember I used the instructions verbatim out of the box and it worked for me. I did have an old nvida card in my machine before the 4650. I also checked Gigabyte and ATI websites for updated drivers and never found any (have not looked for a while).