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I have a "Samsung SyncMaster 2433" monitor and I connect it to my laptop (a ThinkPad W520) with a VGA cable. If I look at the image closely, however, I can see small yellow lines like noise lines all over the monitor moving around.

What can I do to improve the display quality of this monitor and make these noise lines disappear? Will using a DVI adapter help? any other suggestions?

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Try this: see if the lines are still there when your laptop is not plugged into the AC. If so, then it's a ground loop issue and the "solution" is an ungrounded power supply for your laptop – Earlz Aug 27 '12 at 17:43
hmm...interesting....but yeah tried it, lines still there. Gonna try the DVI next... – BdotA Aug 27 '12 at 17:50
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Ah, well I've tried 4 different laptops and 8 different monitors and they all suffer from this ground loop issue if the power supply is grounded. It's usually not small yellow lines though, for me it's a subtle flicker that just catches your eye just enough to bother you – Earlz Aug 27 '12 at 17:51
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BdotA, YES! I actually just learned about this today. I had been wandering about the same thing for 3 years now. Other possible solutions: connect monitor and laptop charger to different outlets, remove the ground plug on one of them, get a 2-prong laptop charger, and finally get a ground noise suppression device – Earlz Aug 27 '12 at 20:52
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Although note, this is still only a problem for analog connections, so switching to digital DVI will fix the problem as well – Earlz Aug 27 '12 at 20:58
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closed as too localized by techie007, Diogo, Doug Harris, Luke, 8088 Aug 28 '12 at 5:56

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3 Answers

up vote 8 down vote accepted

There's a good chance that the noise you see is the result of your VGA signal (which is analogue) not being up to par. Switching to a digital connection will likely (but not definitely) resolve the noise.

DVI can carry both digital and analogue data. You will want to make sure you are using DVI-D and not DVI-A. According to the data sheet for the ThinkPad W520, your laptop has a DisplayPort and can output single-link DVD-D via cable 45J7915. If your monitor supports DisplayPort, you could of course hook that straight up without needing an adapter.

Using a VGA-to-DVI adapter will not help, and may in fact make the problem worse, as that will send DVI-A, an analogue signal, to the monitor.

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thanks for research on Lenovo.. you are correct, I didn't know that...yes it has a DisplayPort ( with a ++P icon ), now I also looked at the back of the monitor and it also has a slot that says "DVI IN" ... so does it mean I can connect that DisplayPort to this "DVI IN" of the monitor? – BdotA Aug 27 '12 at 14:58
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@BdotA Yes, you can use a DisplayPort-to-DVI adapter. Search for the part number 45J7915, or get a generic cable (see also my answer below). – Indrek Aug 27 '12 at 15:01
Ok, I found them..but looking at their pictures: Aren't they too short? how does it even reach from Laptop to monitor? – BdotA Aug 27 '12 at 15:35
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The 45J7915 is actually an adapter rather than a cable. You'd plug a DVI-D cable between it and your monitor. – ChrisInEdmonton Aug 27 '12 at 15:46
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Yeah, I'd say that is correct, BdotA. Just a single-link DVI-D cable will be sufficient (that's all your laptop supports). Monoprice often has the best prices. – ChrisInEdmonton Aug 27 '12 at 15:56
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up vote 5 down vote

Using a DVI adapter connected to a VGA port should make no difference at all. If your laptop has a DVI port then yes, connecting the screen using native DVI should give you a better image.

In general, problems like what you describe are often caused by bad connections (make sure the cable is properly connected to both the laptop and the screen) or bad cables. Getting a new VGA (what you called the "blue cable") cable might help. Finally, I have often encountered problems with long VGA cables. If you are using a cheap cable that is more than ~2m long, that may also be causing your problem.

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+1 for mentioning the length of the VGA cable. I've seen the problems that can cause. – ChrisInEdmonton Aug 27 '12 at 14:41
up vote 2 down vote

If you mean a VGA-to-DVI adapter, that won't help because the video signal will still be analogue. What you'll want is to use a fully digital signal path for the video, that should provide significantly better image quality.

The only digital video input on your monitor is DVI-D, and your laptop has a built-in DisplayPort output. Converters from the latter to the former should be readily available in most computer stores, as well as on eBay (make sure not to buy one that's for Mini DisplayPort).

Alternatively, Lenovo should offer docking stations for your laptop that have DVI outputs, enabling you to use a regular DVI cable from the docking station to the monitor.

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thanks......... – BdotA Aug 27 '12 at 15:03

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