I want my kde to run at 800 X 600 . So I set Modes "800x600" "640x480" . so why is it running 1280 x 740
below is my config file
-----------------------------------------------------------Section "Monitor"
Identifier "Monitor0"
VendorName "Monitor Vendor"
ModelName "v70s"
DisplaySize 320 240
HorizSync 30.0 - 70.0
VertRefresh 50.0 - 120.0
Option "dpms"
EndSection

Section "Device"
Identifier "Videocard0"
Driver "i810"
VendorName "Videocard vendor"
BoardName "Intel 845"
VideoRam 16384
EndSection

Section "Screen"
Identifier "Screen0"
Device "Videocard0"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Depth 24
Modes "800x600" "640x480"
EndSubSection
EndSection

Section "DRI"
Group 0
Mode 0666
EndSection

A couple of guesses... first, are you sure that config file is the one that XFree86 is actually using? Nowadays, it's most likely /etc/X11/XF86Config-4 that will be used, but you can read the first few lines of /var/log/XFree86.0.log or /var/log/XFree86.9.log to see which one is being used.

Also, look through the log files for any warnings or errors about unusable video modes. It's possible that it can't figure out the correct monitor settings and refresh rates for 800x600, and so maybe it defaults to a resolution that it knows how to use.

I checked my /var/log/XFree86.0.log it said theat it was using /etc/X11/XF86Config. I also checked I have know /etc/X11/XF86Config-4 file. I am going to check more carefully for errors about video modes.

the problem was I had to reboot. I assumed that when I logged out and in the new resolution settings took affect. I made that assumption based on the fact that the screan turned off and on and made that pop sound.

Aha, yes, that could be the reason. Actually, you would not have needed to reboot - there are a couple ways to get X to restart. Assuming you get a graphical login screen, there may be an option from there to "restart X server" - if there is not, there may be a way to enable such a thing in your configuration settings.

But perhaps the easiest way to do it is this: open a terminal window, and become root (type 'su' and the password). Then type 'init 3'. That will shut down your GUI, and should take you to a normal console. You should still be root (if not, login as root again); then, simply type 'init 5' to start up X again. It'll probably go back to your graphical login screen, and it should use your new resolution. Anyhow, just for future reference - if you ever re-configure stuff in X, that's a much quicker way to restart X without having to reboot.