Re: Quadro FX - Need to force video output on even when display is not detected
You can try the "ConnectedMonitor" option; see the README for details.
The correct value for the option will depend on how your distribution amplifier interfaces with the board. You may need to experiment with different values (try CRT-0 if it's an analog VGA device, or DFP-0 to DFP-4 or so if it's DVI)
If you're using one of the two DisplayPort connectors on either of those boards, you might not be able to get this to work with active dongles if the distribution amplifier doesn't provide an EDID. Passive dongles would probably work, but this is only available for DVI single link.
I'm assuming that your distribution amplifier is an analog device, since this seems simplest.