i810 vs. intel: frequency differences?

[Tom London]

Running xorg-x11-drv-i810-1.6.5-19.fc7, I've noticed that seem to
drive different monitor frequencies for the same
monitor/settings/xorg.conf.

Running on two different LCD monitors, if my xorg.conf says 'i810', I
consistently get Horiz rate of 79.8kHz and Vert rate of 74.6Hz.

If I only change i810->intel and restart X, I consistently get Horiz
rate of 83.0kHz and Vert rate of 77.8Hz (the last is above supported
rate (~75Hz) for both monitors).

I've also noticed inconsistencies between the rates reported by my
monitors and that reported by xrandr when I run with 'intel': xrandr
reports Horiz is 80kHz (vs. monitor reporting 83kHz) and Vert is 75Hz
(vs. monitor reporting 77.8Hz).

Anyone have idea what could be causing this?

The only 'workaround' I've devised is to run 'xrandr --rate 60'.  That
puts the monitor 'within supported rates'.  When I do that, xrandr
says it is supporting 59.9Hz while the monitor says it is getting
60.1Hz....

Any suggestions?

tom
-- 
Tom London