Re: QuadroFX 1500 (Compaq nw9440) Can't change resolution
I wouldn't expect modelines to work for a DFP under most circumstances unless you obtained them from the EDID in the DFP.
Have you attempted to just request the modes you want (without modelines)? If so, please start X with the following command:
startx -- -logverbose 6
and then generate a new bug report while the problem is present.