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I'm using i3 window manager (shouldn't be relevant) on 3.6.2-1-ARCH with XServer (ver 1.13.0), xrandr (ver 1.3.5) and RandR (ver 1.3). Graphics card is Intel HD 4000.

I have set up my screen using

xrandr --output VGA1 --auto --left-of LVDS1

The issue is that my right screen (VGA1) has horizontal lines flickering up and down (refresh frequency problem perhaps?). My monitor reports that the input is:

1440x900
H: 56KHz V:60Hz
Analog Input

xrandr reports VGA1 as:

VGA1 connected 1440x900+0+0 (normal left inverted right x axis y axis) 410mm x 256mm
   1440x900       59.9*+   75.0  
   1280x1024      75.0     60.0  
   1280x960       60.0  
   1366x768       60.0  
   1360x768       60.0  
   1280x800       74.9     59.8  
   1152x864       75.0  
   1280x768       74.9     59.9  
   1024x768       75.1     70.1     60.0  
   1024x576       60.0  
   832x624        74.6  
   800x600        72.2     75.0     60.3     56.2  
   848x480        60.0  
   640x480        72.8     75.0     66.7     60.0  
   720x400        70.1  
   1440x900_75.00   75.0   

I have tried changing the options around (including adding new modes, e.g. 144x900_75.00) with no luck. How can I get rid of this annoying flickering?

UPDATE: I have just realized that the flickering of secondary screen only happens when laptop is plugged into power supply - while on battery problem does not exist. Any way to fix it?

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how are your other display(s) connected? a lot of video cards have issues when outputting in different formats (dvi and vga) simultaneously because it requires using 2 separate graphics engines. And most integrated graphics cards cant do both at the same time. –  h3rrmiller Oct 22 '12 at 15:34
    
@h3rrmiller: I forgot to mention that the machine running my Arch is a laptop. The primary output (LVDS1 is laptop's screen) whereas VGA1 is a separate LCD connected by a VGA cable. I am not quite sure how hardware deals with it (or how to find out which port is controlled by what) - would appreciate any hints :). –  norfavrell Oct 22 '12 at 15:37
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LCD should not flicker, regardless of the refresh rate. Try using OSD menu of the monitor and adjust the clock sync rate (or similar option). –  gorkypl Oct 22 '12 at 18:09
    
@gorkypl: Tried that. IT's not really the LCD flickering, it's horizontal lines flickering across it. –  norfavrell Oct 22 '12 at 18:16
    
is it flickering? or are you getting artifacts? either way it sounds like a driver issue. I had the same thing when getting my eyefinity card up and running –  h3rrmiller Oct 25 '12 at 12:54
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1 Answer

Apparently this is due to a ground loop problem which exists on some laptops. Detailed explanation (and dirty fix) can be found here.

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I used this fix a while back. I eventually bought an ungrounded charger though. –  paraxor Apr 15 '13 at 23:14
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