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I have just installed Ubuntu on a Dell Inspiron 15. I'm using an AMD Radeon HD 7730M with the latest beta drivers installed. Whenever I try to plug in a dual monitor I get incredibly bad screen flicker and my launch bar is displayed in the middle of my screen, but still responds as if it were on the left at it's normal position. See this image.

Any idea what's causing this? Could it be the beta drivers? Have I not set something up correctly?

Nanor
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  • Note: flickering on the external monitor can sometimes be solved by running a laptop off of battery. Noise from the power supply can appear on the external screen, somehow. – Richard Feb 09 '15 at 23:59

2 Answers2

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Figured the problem. Hopefully this can help someone. I never mentioned in my question that I was using a hybrid graphics set up with a 7730 AND an Intel 4000. When you plug in a separate monitor you get a mad flickering action going on. A temporary solution someone found is listed here.

This worked a treat initially, however when I opened the display options and moved my external monitor to the right hand side of my laptop screen that's when the problem happened. I looked at the command I used to stop the initial screen flickering:

xrandr --output VGA1 --auto --left-of LVDS1 --output VGA1 --scale 1.0001x1.0001

I noticed the bit that said --left-of. This would be fine if the monitor was to the left of the main display but it no longer is! Your command should simply be

xrandr --output VGA1 --auto --right-of LVDS1 --output VGA1 --scale 1.0001x1.0001

and everything should be working fine.

Nanor
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  • I have the same problem, but i want to change the screen to left, and it start flickering again. how can solve it? :-\ – Tal Jul 02 '15 at 16:43
  • using --scale 1.0001x1.0001 was the only thing that worked for me on Ubuntu 18.04 – alexisrozhkov Feb 10 '19 at 19:47
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I also had a flickering with my second monitor. Interestingly only when I used DisplyPort. I had no problem with DVI. I could solve the problem within the AMD Catalyst Control Center by setting the Image Options from "Use display for scaling" to "Use graphics processor for scaling" on both monitors. Now I have no problem with flickering anymore.

See image:

Card: AMD Radeon HD 9600

Driver: 13.35

Catalyst: 2.20

RandR: 1.3

Ubuntu: 12.04

Community
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Jürgen Brandstetter
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