Re: Can't output to Sony TV via DVI
If you're able to get the SONY DFP working after swapping in a different display, what you could do (after the SONY DFP is working to your satisfaction), is run nvidia-settings, and then the X Server Display Configuration section, and click the Detect Displays button. If your SONY is accurately displayed (instead of whatever you plugged in initially) then you can capture its EDID. Next, go to the GPU section, then the DFP section, and click the "Acquire EDID" button, and save the EDID to a file. That EDID can then be used with the CustomEDID option (see the driver README for more details).
However, if the display can't be detected at all, then none of the above will work. You can still attempt to force the driver to use the custom modeline that you believe works by setting the ConnectedMonitor option to DFP, and specifying the modeline you wish to use.