If I'm interpreting your writing correctly, you're stating that you have an actual graphics card, and not an integrated one, correct?
If this is correct, then your motherboard integrated graphics will be disabled, and the hdmi port will not be working, so plugging the HDMI into your motherboard will not produce any output (as far as I know, someone correct me if I'm wrong)
If your graphics card does not have an HDMI port, you can either use an adapter to HDMI, or you could even disable your graphics card and use the onboard graphics each time you want to use the HDMI output.
On a side note, make sure that you're switching the display from your monitor to your TV.
Edited by bradumd, 20 October 2010 - 12:31 AM.