X stuck at 1600x1200@60 on Radeon

[salfter]

I've set up AMD64 Gentoo on an Athlon 64 box with a Radeon 7000 and want to get X and KDE going. The appropriate ebuilds have been installed, I've run xorgconfig to generate /etc/X11/xorg.conf, and I've tested it with startx.

It comes up, but even though the Display subsections in xorg.conf don't mention any resolution higher than 1280x1024, X insists on running at 1600x1200 at 60 Hz. Pressing Ctrl-Alt-+ masks off part of the display, but my monitor still says it's running at 1600x1200 at 60 Hz. Ideally, I'd want it to run at 1280x960 at 85 Hz (what it runs at under WinXP), but I'd even settle for 1280x1024 or 1024x768 right now.

The driver appears to be querying the monitor for its specs and is automatically driving it at the highest resolution possible, my choices be damned. I've tried including NoDDC and IgnoreEDID among the device options with various combinations of 1, 0, on, and off, but none of it seems to make a difference. In all cases, /var/log/Xorg.0.log reports that X has retrieved the monitor info and is acting on it. There must be an option to disable this behavior, short of a hardware solution (HD15-to-HD15 connector with the pin that carries DDC info left disconnected), but I can't seem to figure it out. Any clues, anyone?

Here's the xorg.conf I'm using (comments stripped out for brevity):