Flickering flatscreen with DRI-accelerated Radeon 9200

[Philip Jägenstedt]

Hello!

I have an ATI Radeon 9200 which is connected via DVI to my NEC LCD1920NX 
(a flatscreen monitor). Ever since I got this monitor (~1½ years ago) 
I've not been able to use 3D-acceleration (since I got my radeon to 
escape proprietary drivers this feels especially annoying).

Now I'm migrating to xorg, thinking that the problem may have been 
fixed, or that the xorg community can help me help find the problem and 
fix it.

The problem:

When something onscreen updates/changes too quickly, I get 
flickering/noise. The "flickers" are short horizontal lines in various 
colors (red, green, blue and maybe white). This has happen even if I am 
not using 3D, although I haven't noticed that happening for quite some 
time now. If I run glxgears the flickering is *quite* noticeable and the 
screen will even go black sometimes (complaining that it is out of sync 
I believe). Clearly this makes using anything 3D impossible.

This weekend I installed windows 2000 on a spare hard drive and it turns 
out that 3D works without flickering there, so it is not simply a 
hardware problem.

I have tried xorg X11R6.8.1 and todays CVS, but neither have given 
different results. Before I was using XFree86 4.3.0. My system is debian 
unstable, but no other distros I have tried have been any different.

Attached is my xorg.conf, if that will provide any clues. The sync 
values are from the manual. The monitor is supposed to run at 60Hz, and 
I have theories that it is actually running at some other frequency, but 
no ModeLines I have tried have made a difference. I have tried setting 
alot of different option in XF86Config-4/xorg.conf without successs.

I would appreciate any help so that I will be able to use 3D again. 
Anything that might be useful for tracking down the problem I will 
gladly provide.

Random system information:
OS: current debian unstable
Motherboard: VIA KT333
Processor: AMD Athlon 2000+
Graphics: ATI Radeon 9200
Monitor: NEC MultiSync LCD1920NX

// Philip Jägenstedt