...clear with a graphic card? well i used to have a old mother board with p4 processor at that time there was intel extreme grpahic in it i mean in bulit and any video was very clear. but now i bought a amd athlon 3000+ 939 pin and asus a8n-e motherboard with nvidia leadtek 7800 gt the videos are not so clear. i tried this with other graphic card like nvidia5700 and nvidia4000 also why????and is there any way i can improve this or get rid of this problem

Something that you might try, if you haven't already, is to simply switch the graphics card you are installing to another from PCI port, and see if the problem isn't with a defective port and not the cards themselves. Also, since you do have a new motherborad you might want to try adjusting the settings for the video cards as well.