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I have a dual screen setup with two AOC e2450Sw monitors connected to a laptop. The laptop has one HDMI and one VGA output. When one of the monitors is connected using VGA, it flickers or displays static noise. The flickering is fairly subtle and only visible on darker colors. But it is there and noticable and appears like horizontal lines.

The problem only appears on the monitor connected to the laptop using the VGA cable. If I swap the monitors, the one connected using VGA is displaying the flicker but not the one connected using HDMI. The simple solution would ofcourse be to connect both monitors using HDMI, but since the laptop only has one VGA and one HDMI out that isn't possible. I've tried tweaking the monitor setting using the OSD menu, but it had little or no effect.

Update: After several more trouble shooting hours, it seems the problem is not related to the monitor or VGA cable as the problem persists even if I swap the display with another brand and different cables. So it may be the graphics card? Intel HD Graphics 4000. The laptop is Acer Aspire E1-571.

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2 Answers 2

I would say that either the VGA cable or the VGA connector on the laptop is damaged.

Have you another cable you can try?

Also try screwing in the cable at both ends to eliminate any movement.

Remember that VGA is an analogue format and so some flickering may occur, the quality of the signal is highly dependent on the connection and the quality/length of the VGA cable.

With HDMI, the signal is digital and so the output is far less dependent on the cable quality.

Oh, one other thing. Even with a good VGA cable, the monitor will probably not be able to do as good a job as with HDMI, especially at really high resolutions - what resolution are you using? That's because the analogue signal has a limited bandwidth.

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I guess the VGA connector on the laptop may be damaged. But it's brand new and it is not visibly damaged so it seems like a long shot to me. –  Björn Lindqvist Jan 22 '13 at 16:36
What resolution are you trying to achieve with the VGA output? Have you tried a lower resolution to see if the flickering is any better? Is the flickering bad enough to video? Perhaps you could post a video if so. –  Julian Knight Jan 23 '13 at 21:36
The flickering is the same no matter the screen resolution. It's not bad enough to video record. –  Björn Lindqvist Jan 24 '13 at 9:24
Ah, when I read your last comment, another thought came to mind. What lighting do you use? Some lighting can make the inevitable slight flicker on VGA output seem worse? Old fashioned incandescent lighting is "best" as it doesn't really have a flicker whereas fluorescent lighting is the worse. If not that, then I think we've eliminated everything except the graphics output of the PC so I'd have to conclude the there is either something wrong with it or it has a poor design. –  Julian Knight Jan 24 '13 at 21:25

You may try a shorter cable. It seems that the integrated graphic card does not send powerful-enough signal.

I had similar problem with 5 metres long cable - once connected to integrated notebook D-Sub port, display flickered; once connected to PC (with graphic card, over DVI-VGA converter), everything worked.

Same setting but with shorter cable (2 metres) worked with both PC and NB, so I suspect the integrated graphics…

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