Intel and radeon have this option available, which Xorg.0.log reports is unused with nv. What is available that corresponds to its result for nv, necessary when EDID is defective and the CRT supports up to 2048x1536, which nv assumes is wanted, but less than that is actually wanted as initial X mode? The nv man page doesn't seem to have anything close. Without an equivalent, either xorg.conf must be used, or else both 50-monitor.conf and 50-screen must be used, to get both desired startup resolution and DPI.