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#1 2009-03-16 13:02:03

rekado
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From: Shanghai, China
Registered: 2009-01-13
Posts: 98
Website

[SOLVED] Screen constantly flickers vertically after GRUB

Hi all,
I finally bought myself a new PC with the following basic configuration:

ATI Radeon 3200 + AMD Phenom II X4 940

After a complete FTP installation of Arch Linux x86_64 I tried to setup X. Keyboard became unresponsive as I forgot something so I had to force a reboot. Since then right after selecting the to be booted kernel in GRUB the screen flickers. Funnily, this is only a vertical flicker. Independent on the framebuffer settings the flicker offset is almost one line, so that I see each line twice. Starting X (higher resolution than the console) the flickering makes it impossible to read anything clearly.
When shutting down, I noticed that for a short moment the flickering would completely halt. This happens when the message "Saving System Clock" is being displayed. After that the flickering continues until the PC has shut down. This is very curious, I thought and then started X again after rebooting (the PC was turned off the whole day). Still, the same flicker from right after GRUB. I started glxgears from the xterm (haven't had the chance to install any other terminal emulator so far) and suddenly the flickering stopped. If I abort glxgears the flickering returns.

I assume that a higher CPU load makes the flickering disappear. Where might the flickering come from? It is a fresh install, everything new. I already turned off the internal graphics chip (and blindly activted again) in the BIOS but to no avail.

I would appreciate any comments or questions!
I'm pretty sure it is nothing to do with the hardware (don't have another graphics card here to prove that, but the PC is bought yesterday) and is nothing to do with Xorg either (even though an aborted X-test seems to have triggered this phenomenon). Is there a chance to clear the video BIOS or something like this?


EDIT:
I know now what it is related to: Cool'n'Quiet (frequency scaling), When I turn of Cool'n'Quiet in the BIOS everything is alright. But this means that the CPU runs at 3.0GHz all the time which I really don't want it to. Even running at 2.3GHz doesn't help. Only when the CPU is maxed out the flickering stops. Weird.
Any ideas?

Last edited by rekado (2009-05-07 08:48:27)

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#2 2009-03-16 14:03:27

rekado
Member
From: Shanghai, China
Registered: 2009-01-13
Posts: 98
Website

Re: [SOLVED] Screen constantly flickers vertically after GRUB

The uber-weird thing is: I deactivated my internal graphics card again and booted for several times. I heard that the PC rebooted automatically again and again. Then I don't know if I changed it or it was changed automatically, but I had internal graphics again (I did try to turn it on blindly, don't know if I succeeded, though) and the flickering was gone.

Well, yesterday this also happened but today in the morning it was back on, flickering. I really don't know what the problem is. Now Cool'n'Quiet does work.

Hmm.


EDIT: I just turned the PC on again after leaving it off the whole night and the problem is back. Flickering unless I do not use Cool'n'Quiet.

Last edited by rekado (2009-03-16 23:19:18)

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#3 2009-03-17 01:33:51

rekado
Member
From: Shanghai, China
Registered: 2009-01-13
Posts: 98
Website

Re: [SOLVED] Screen constantly flickers vertically after GRUB

I just found an unsolved thread about a very similar issue here:

http://forums.amd.com/game/messageview. … erthread=y

This however occurs under Windows. So I think it is a hardware issue related to Cool'n'Quiet. I will try to get support from AMD or Gigabyte then.

Last edited by rekado (2009-03-17 03:07:20)

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#4 2009-05-07 08:30:41

rekado
Member
From: Shanghai, China
Registered: 2009-01-13
Posts: 98
Website

Re: [SOLVED] Screen constantly flickers vertically after GRUB

It turned out to be both a problem of the RAM and the BIOS.

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