VGA display mode

kevin,thanks for your reply~

in 25MHz mode,the parameters are as follows:

format horizontal parameters vertical parameters

640*480,60Hz, 640 16 96 48 480 11 2 31

then in 50MHz mode,the parameters are replaced by :

format horizontal parameters vertical parameters

1280*480,60Hz, 1280 32 192 96 480 11 2 31

but I also get the message from VGA says"the ouput data is too much to display",then I change those parameters according to the webhttp://martin.hinner.info/vga/timing.html (http://martin.hinner.info/vga/timing.html)

format horizontal parameters vertical parameters

800*600,72Hz, 800 56 120 64 600 37 6 23

in 25MHz mode,I can get nice image,but when I try to change the pixel frequency to 50MHz, I cannot get any image,there is always "ouput data is too much to display" in the VGA display screen~

I have think about the VGA display mode for serveral days,but I also cannot get any meaningful conclusion~