Well I made some progress today on solving this issue.
It seems that the ATI 3.9.0 fglrx driver appears
(according to fglrxconfig) to support both 1600x1200
and 1400x1050. I have found that 1600x1200 is noisy
with white horizontal streaks on our ViewSonic VP201s
connected by the digital interface. Also the 1400x1050
doesn't really appear to exist in the fglrx driver.
Use of that mode drops the display back to 1280x1024.
However I was able to create a 1400x1050 that worked
by adding the modeline...
# 1400x1050 @ 75.00 Hz (GTF) hsync: 82.20 kHz; pclk: 155.85 MHz
Modeline "1400x1050_75.00" 155.85 1400 1496 1648 1896 1050 1051 1054 1096 -HSync +Vsync
and using 1400x1050_75.00 instead of 1400x1050 in the Modes for
Screen0. This gives a working 1400x1050 without static and
excellent framerates for glxgears (3000 fps) on my Radeon 9600XT.
I then tried to do the same for 1600x1200 using a lower
horizontal refresh (55 Hz). However it appears that the fglrx
driver ignores any additional modelines for the 1600x1200 resolution
and uses the built in defaults rather than the modeline I enter
as 1600x1200_55.00. Any idea if we can override this? I suspect if
we can just tweak down the refresh rate from 60 Hz to 55 Hz at
1600x1200 that the static may disappear.
Jack
