Two display anomalies

[Bob Chiodini]

On Tue, 2005-09-06 at 20:58 -0400, Matthew Saltzman wrote:
> (1) 
> Video card: NVIDIA GeForce 2 MX (generic)
> Monitor: Samsung SyncMaster 930B (flat panel)
> Driver: nvidia (the commercial one), but it happens as well with nv.
> Resolution: 1280x1024, 32-bit color or 16-bit color
> Sypmtom: Monitor flickers as if it's synching at very low rate.
> The monitor reports that it is syching at 75Hz, but I still see flicker.
> 
> (2)
> Video card: ATI Radeon Mobility 7500 in an IBM Thinkpad T41.
> Driver: radeon
> Kernel: kernel-2.6.12-1.1398_FC4
> Kernel option: video=radeonfb
> X: xorg-x11-6.8.2-37.FC4.45
> Symptom: When I use the VGA-out jack to connect to an overhead projector 
> or external monitor, the projector image ripples slowly, as though (very 
> narrow) waves are passing over it.
> 
> In FC3, this behavior varied with the kernel version.  In FC4, I need this 
> kernel in order to get proper ACPI behavior, so I haven't tested much.  In
> WinXP, the display is rock-solid.
> 
> For (1), could this be the monitor?  It's brand new.  I also recently 
> installed a TV tuner card, but that doesn't seem to be too likely a 
> culprit.  I didn't *think* I was seeing the flicker before that, but it's 
> my wife's monitor, so I didn't spend much time with it.  My machine (CRT, 
> no TV tuner) is rock solid.
> 
> If it's not the monitor, what should I be looking for to further isolate 
> the problem?
> 
> For (2), I'm pretty convinced it's a bug, but I' not sure what component 
> to report it against.  In FC3, it varied with kernel version, with 
> whatever XFree/xorg was installed.  So I'm sort-of thinking kernel.
> 
> Thanks for any suggestions.
> 
> -- 
>  		Matthew Saltzman
> 
> Clemson University Math Sciences
> mjs AT clemson DOT edu
> http://www.math.clemson.edu/~mjs
> 

Matthew,

1) Try lowering the vertical refresh to 60 Hz.  I'm not familiar with
that display, but both the Dell and the Viewsonic recommend 60 Hz.

2) Are the vertical and horizontal rates the same between Windows and
FC4?  

Are they the same laptop?  

If you answered yes to both then I'm stumped.  

But...

If the refresh rates are not same then adjust FC4 to the same as
Windows.  

The problem sounds like a bad/low quality cable. Cable performance will
get worse as the refresh rates go up.  Could also be a grounding problem
inducing hum in the video signal.

If Windows and FC4 are not running on the same laptop then I would
suspect a hardware problem with the FC4 laptop. 

Bob...