HDMI not working with GIGABYTE GV-R687OC-1GD Radeon HD 6870 1GB 256-bit GDDR5

[ged]

Hi,

I've a GIGABYTE GV-R687OC-1GD Radeon HD 6870 1GB 256-bit GDDR5 on a ASUS P8Z77-I Deluxe LGA 1155 Intel Z77 motherboard.

I've a main display connected to a DVI port.

I would like to connect a TV to the HDMI port and get video and audio on that TV.
I've plugged in an HDMI cable, but no signal registers on the TV. It stays blank.
System preferences does not seem to see two monitors.

What did I miss?

Thanks,

 

[Asus-Freak]

Try typing this at the Chimera boot screen:

AtiConfig=Bulrushes