Monitor Modeline Not working???

[perplexabot]

Hello all. I've spent a good amount of time trying to research my monitor specs. I'm trying to achieve higher resolution because the default resolution is 800x600. I used these two guides to help me configure xorg.conf file:

http://ubuntuforums.org/showthread.php?t=83973
http://www.x.org/archive/X11R6.8.0/doc/xorg.conf.5.html

i added the modeline under Monitor. I used a modeline generator to get:
Modeline "1280x800@66" 94.54 1280 1312 1664 1696 800 816 825 841

after all this i went to system settings and checked Monitor size and orientation only to find that my highest resolution is STILL 800x600. Can anyone let me know what i'm doing wrong or what steps i still have to do? I must state that despite the long search for my monitor specs i still ended up using my own specs, because i could not find my monitor's hsync and vsync rates, will this cause any problems?

[krtsa91]

have you tried to install latest drivers of you graphic card?

[perplexabot]

nope. I just assumed that i didn't have to. When i run bt5 off of a usb my resolution is perfect. Could it be that i have to install the drivers as u said? I will give that a try. thanks for the reply.