card , and a nevidia geforce? each time i connect the screen to the geforce nvidia 8400gs card the screen stays blank as if the computer is still off, but when i connect it to the built in video card , it starts normally, nothing is wrong with the video card , and nothing is wrong with the screen , but each time power cuts off same problem happens, they perfectly worked together before now the geforce is not working only on my screen, screen is a brand new LG lcd , no adjustments to the screen it has auto adjust , the problem is not from screen neither the graphics card when i connect it to the old screen it perfectly works , please i need a professional! 
reply is much appreciated thank you.
reply is much appreciated thank you.