Ubuntu 11.10 Radeon 5670 card using open source driver.

I am trying to set the display rate manually so I can hook the desktop up to an HDMI switcher so the computer will be available to multiple tv's (plasma and led). When I hook this up via hdmi I can't get any picture. currently the hdmi to dvi cable works and detects my sony monitor so I'm guessing it has something to do with an auto-detect feature?

thanks for your help.