I posted back in January about my plans to use the HDMI port with a TV:

 
Fast forward to today and this is driving me nuts. I want to hook up my 570 to a new Insignia HDTV via the mini HDMI port. I have a good quality cable that I know works fine. When I make the connections, the computer recognizes the TV just fine, shows the model number, supported resolution, etc.  However, on the TV end, it reports no signal!
 
Through troubleshooting, I discovered that If I go DVI from the card to the TV with the DVI to HDMI adapter, it works fine, video and sound.
 
Also through troubleshooting, and I can't remember exactly, but I disconnected both DVI cables from the card and only had the HDMI connected.  Saw nothing at bootup, no bios screen, but there was a momentary flash of the windows logon screen and then it went away.
 
Can someone please help me so that I can get picture and sound from the mini HDMI port on my card? I am using the current 353.49 driver.

Yes. Tried both HDMI inputs on the TV, and switching the inputs yes

Hmm, no humidity here and I just recently blew out all the ports with a can of air because of construction dust... I'll try that but I don't think that's the issue in my case.

It's not a bad port on the card because when it's the only monitor connected, at boot up, it shows signal on the screen.  Then as soon as you get into windows, the signal is lost....

I'll check on the firmware update, not sure about that actually. Will update after I look into it, thanks!

 
Make sure the settings in the TV and PC are set to HDMI. Use a different cable too.