NF-CK804 isn't the actual model of your motherboard. Use something like Everest to check:
http://downloads.guru3d.com/download.php?det=1072
For the graphics card problem, check that you have the latest motherboard drivers also installed. What power supply are you using? PCI-E requires a unit capable of 26A on the +12V rail to run properly, so test out a quality one if your's doesn't meet the requirement.
From a quick Google I can at least gather that your motherboard uses an NVIDIA nForce4 chipset, so I don't see why you would have the ATI Unified AVStream Driver installed. If you want, boot into Safe Mode by hitting F8 during the boot screen, and uninstall it.