Why do I have to switch on my monitor first, then my computer for a successful bootup? If I switch on my computer first, only the Windows wallpaper shows up - no taskbar and no icons!
Basically what happens is during the boot process DDC (Display data channel/ Windows plug and play) uses as a communications link between your monitor video card and windows OS. It goes out and looks at the monitor’s EDID information (in the monitor’s memory) and tries to determine the best or optimal resolution and refresh rate. If the monitor is off the communications channel does not work and the system may boot to some unknown resolution and refresh rate.
Jim Witkowski
Chief Hardware Engineer
Cornerstone / Monitorsdirect.com
I have this problem before. ATI let you set the refresh rate and resolution manually. If you manually set the refresh rate and resolution then the setting will be not change even you boot your computer without turning on the monitor.