Video card or mother?

Hello, there is the following problem while working behind a PC screen on an empty place was covered with white stripes on grey background, the subsequent reboot led to the fact that after you download the windows icon the screen went to gray and to reach out to PC's was unreal
demolition driver and setting a new one through safe mode, the situation is not changed, cleaning the slots and the video card too. Reinstallation of the system improved the situation, the computer starts but the slightest load again fell the image ( and the sound system worked,as he launched a film), switched to integrated graphics and everything works without any problems. His tried to insert into another PC and everything works fine. What could be the problem? Thanks in advance.