On Tue, 2005-09-06 at 23:01 -0400, Matthew Saltzman wrote: > On Tue, 6 Sep 2005, Bob Chiodini wrote: > > > 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. > > Is this an xorg setting? The refresh rates are what is selected when I > run system-config-display. There doesn't seem to be a way to set this in > the monitor menu. How would I set it? > You need to manually edit /etc/X11/xorg.conf to change those settings. With my flatpanel monitor (samsung syncmaster 213T) I had to manually change the VertRefresh from the range of 56.0 - 75.0 which was set by system-config-display to a range of 60.0 - 60.0 in order to get the monitor to allow the maximum resolution of 1600x1200. Did not have to change the HorizSync settings at all. > > > > 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. > > Yes, it's the same laptop running WinXP and FC4 and FC3 with several > different kernels. > > > > > 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. > > That's two suggestions for the cable. I will try some others, but it's > not clear why the same projector and same cable and same hardware behaves > differently when I use different software. > > Thanks for the suggestions. > > > > > Bob... > > > > > > > > -- > Matthew Saltzman > > Clemson University Math Sciences > mjs AT clemson DOT edu > http://www.math.clemson.edu/~mjs >
