Screen blacks out before login

My screen blacks out today when I tried to turn on my computer, there is a signal "DSUB" at the right upper coner, I can't even press F8 to enter the save mode, and I tried to reboot my PC but still doesnt work... is there anyone can help?
 
Bad video card, video driver or hard drive... Did you download or install anything right before this problem showed up? Laptop or desktop?
 
Back