I bought a new video card for my computer. a HIS X1650Pro. When I read the user manual on the enclosed CD it told me to uninstall my present video drivers, turn the computer off then install the new video card, power up and then install the new drivers. After installing the new video card it would not boot up. The monitor is just blank. I thought maybe something was wrong the new new video card so I took it back out and reinstalled the old video card and turn the machine back on. Monitor is still blank. The little light that normally flashes for the hardrive while the computer is booting up does not light up now. Inside the computer the fans are running and the harddrives are running, but nothing on the screen. Help please.