External Monitor Resolution Problem

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http://forums.fedoraforum.org – Hii I've a VGA monitor which has max. resolution of 1600x900. The problem is that, when i connect this monitor, there is only two resolutions i can select. 1024x768 & 800x600. the monitor shows as "Unknown Display". So, everytime when i connect, i had to 1. create the modeline for 1600x900 2. add the modeline to VGA1 via xrandr. Is there anyway to resolve this? And if i booted up the PC with VGA connected, it shows some display output error. (HowTos)