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Old 02-10-04, 04:02 PM   #1
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Join Date: Feb 2004
Posts: 1
Default Driver causes screen to flicker


I am having trouble with nVIDIA's Linux driver causing the screen on my notebook
to periodically flicker.

I am using a custom modeline for my notebook, since it has a non-standard native
resolution. To produce the modeline and get the OpenGL acceleration I need, I
am using nVIDIA's Linux driver. Unfortunately, it causes the screen to flicker
at seemingly random intervals. If I let the computer just sit, it seems to be
fine; however, once I start performing tasks and moving the mouse, at random
intervals the screen will flicker.

The flicker is usually too fast to describe; however, sometimes it can be made
out. There appears to be white lines. Each is 1 pixel high, equal length and
spaced at even intervals. It appears to be a timing issue, as if the remainder
from some calculation is accumulating and visually displaying itself when it has
accumulated enough to overflow the calculation.


I have spent a substantial amount of time trying to resolve the issue. Since it
appears to be a timing issue, I have tested numerous modelines. I have
generated some using online modeline generators and some by hand using the
XFree86 Video Timings HOWTO. Different modelines do affect the frequency of the
flicker and the length of the white lines. I have settled on my hand generated
modelines, since they produce the best results and the refresh rates closest to
the screen's capabilities.

Inability to resolve the issue with accurate modelines led me to try the open
source driver by changing 'Driver "nvidia"' in the 'Device' section to 'Driver
"nv"' Interestingly enough, this seemed to eliminate the flickering.
Unfortunately, I need the nvidia driver to get the desired OpenGL performance,
so this workaround can only be used to help track down the source of the

I know of two other individuals who have the same notebook and are also running
Linux on it. Both have experienced the same behavior. One is running an older
version of Redhat. He was able to eliminate the flickering by using the
1.0-4363 driver; however, I cannot use that version on Fedora.


The notebook is a HP zd7020us. I am running Redhat's Fedora Core 1 with the
2.4.22-1.2149.nptl kernel and nVIDIA's linux driver version 1.0-5336. The
modeline that I am currently using is

ModeLine "1440x900" 104.76 1440 1472 1872 1904 900 903 904 917 # 55.0kHz, 60.0Hz

This is the notebook's display's native resolution and maximum refresh rates.
The video card is a nVIDIA GeForce4 (FX) 448/5600 Go with 64MB of video RAM.

If anyone has any ideas, or has/is experiencing the same behavior, please let me
know. Thank you.
Thank you for your time and help,
Tom Lanari
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