So, when you plug in a VGA cable and connect to a monitor, and leave the HDMI output alone, you get no picture? What about when you plug in via HDMI, then get to the desktop, and plug in a VGA monitor as well? Windows finds nothing? Have you tried going to the display settings and forcing windows to turn on the VGA output?
After that, i guess it might be a video card/mobo BIOS settings issue? Or the card is broken.