Arch Linux

Orim

Member

Registered: 2009-12-10

Posts: 61

Screen "twitches" when window is open in gnome

Hi there.

Sorry for the stupid subject, I have no idea how to describe it better in one sentence.

The problem is this:
When I open a window in gnome the entire screen (not just the window) begins to jump a few
pixels from left to right and back again. It only does so when a window is open.
I thought it might be my experimental amd video driver but it also happens with the vesa driver.

The screen is a pretty expensive LCD with a standard resolution of 1600x1200 pixels.
When I lower the resolution to 1280x1024 the twitching stops which is funny. Well, not really.
Of course this looks like a problem related to the LCD but I don't get why it only happens when
a window is open.
So this looks like a problem with the graphics card then, doesn't it?
Or do I need some important option in xorg.conf? I don't have a xorg.conf by the way...

X starts without errors but the following warnings:
(WW) Open ACPI failed (/var/run/acpid.socket) (No such file or directory)
(WW) VESA(0): Unable to estimate virtual size

Any ideas?

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 19,804

Re: Screen "twitches" when window is open in gnome

What is the interface to the LCD?  If it is a digital link such as DVI or HDMI, I have no suggestion.

If you are using VGA, it turns out there is no clock signal to actually clock the pixels to the screen.  The LCD has a controller that measures the time between horizontal sync pulses and recreates a clock using a phase locked loop.  Sometimes, the phase of that signal is such that the reconstructed clock edges occur too close to where the pixel data are changing.

Most LCDs with a VGA interface allow you to change the phase using an on-screen menu.  A really good test pattern for setting the phase is a full screen "checkerboard" of black and white pixels.

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Orim

Member

Registered: 2009-12-10

Posts: 61

Re: Screen "twitches" when window is open in gnome

Thanks for your answer and a happy new year

The LCD is actually connected via DVI it doesn't even have any analog interfaces.

I have the same problems in xp and don't have any when I connect the LCD to another PC.
So the only thing left is the graphics card and/or the shitty amd drivers.
I will contact Gigabyte to ask if they will give me a new mainboard (warranty is still valid).

I guess this case is closed, thanks.