Problem with graphic card after a restart

Hello,

I'm having a graphic card which has a problem ,I installed it in my pc than the computer booted up than I restarted the computer but it does not want to display on the monitor ,but if I plug it out and put the vga on the internal graphic memory it works perfeckly but if I put it back again later the graphic card the copmuter Starts normaly but when I shut the computer down again it becomes a problem.model Nvidia grforce 520 1GB.please help me if there is solution to it I tried this at other desktops but still does the same