I have PNY-nvidia quadro 4000 with 3 display ports on my ubuntu 12.04 machine. I have successfully configured two monitors using 1 DVI-L port and 1 of the two display ports (with male display port to female DVI-D adapter).
I want to use remaining display port to connect to to a 3rd monitor (using identical Display port-to-DVI-D adapter that is used for my second monitor) but can not get it to work through Nvidia-settings. I can see this third monitor listed into nvidia-settings but when tried to save the x configuration file, it showed layout inconsistencies error :
Metamode 1 of Screen 0 has more than 2 active display devices
Moreover, the blank screen of this third monitor displays a message
Check Signal Cable Analog
Could this be resolved now by using Display port-to-VGA adaptor instead?
x.config needs to be changed manually?