nh420

I turned my pc on one morning and the tower came on but nothing appeared on the screen, and when i turned the monitor off and then back on the power light just goes from green to orange. I thought I may need a new graphics card so I bought one. I installed the card into the PCI slot and plugged the monitor in but it still does the same thing. How do I install the driver if the screen is blank? Please Help Someone!!! It would be MUCH appreciated.