Not a big deal - more a nuisance.

I use a Dell 1703 FP analogue monitor.
During boot, I get a message about analogue input, cannot display this video mode.
After a short delay it carries on and everything works fine.

Looks to me like it has not detected my monitor as an analogue monitor.

How can I change this i.e can I make a change to xorg.conf? Is there a way of respecifying the monitor? (I seem to remember in Debian I could run dpkg-reconfigure .... to change the video.

thank you