Video Card Install, Display Flashes Off and On

I recently installed a Video Card to support dual monitors on a pc. It worked fine until the pc was restarted and when it came back on, the primary display started flashing off and on. I reseated the card, reinstalled the drivers, changed the DVI adapter, etc…I know the cables and monitors are fine, as they work with another pc. The default display works fine, after removing the video card. I am thinking that the pci slot might have gone bad but have no idea how to test it. Is there a way to test the slot specifically? Any other suggestions?