View Full Version : Blue squiggly lines/pixels in dark areas on external monitor

25th January 2013, 05:36 PM
Hi guys,
Got a weird issue here that I can’t seem to find any info on…
I’m running a mid 2010 15” MBP which has the 2 video cards - built-in Intel and Discrete Nvidia GeForce GT 330M with 256MB RAM.

I recently moved house and setup my new office area so I now have my MBP connected to a BenQ G2420HD monitor via mini DVI to DVI adapter.
The last time I had this monitor connected was around 18 months ago and there were no issues.
Now, when connected, I get these odd blue fuzzy lines in dark areas (mainly dark blue or black areas) on the screen:

When I first connected to the screen last week, I thought it may have been because the screen hadn’t been used in such a long time because after a few hours, I noticed it had disappeared and the screen had returned to normal.

Fast forward to today when I had to open Photoshop CS6 and got the following dialog appear:

I’ve never had this message pop up before but I haven’t had the monitor connected since I’ve had CS6 installed either.
As soon as that message popped up, my monitor has gone back to having the bright blue squiggly lines/pixels in the dark areas again and I haven’t been able to get rid of it.

Any thoughts on what’s going on here…?

P.S. I should just mention that the internal screen on the MBP doesn’t exhibit any issues either.

28th January 2013, 01:44 PM
hmm, seems the first image link broke…
You can see it here: Droplr • IMG_0350.JPG (http://d.pr/i/yJwZ)

You can also see what I am talking about in the shadow of the PS dialog box

28th January 2013, 04:58 PM
I had a similar problem on my Benq 22". DVI from my QS2002 was fine, but when I connected my Ubuntu machine via the D-Sub port, I had similar video artifacts. I swapped the cable for one with better shielding and problem is gone.

As to why it seems that CS6-PS is detecting the built-in Intel Graphics - no idea, sorry.

28th January 2013, 05:37 PM
Probably a GPU issue. Does it happen on both graphics cards or just the discrete Nvidia?

28th January 2013, 08:11 PM
When the monitor is connected you can only use the discrete card so I don't know…

29th January 2013, 02:27 PM
So I replaced the DVI to DVI cable with a new one from Belkin. Fixed…

29th January 2013, 07:27 PM
No artifacting and no GPU issues. Hurrah!

29th January 2013, 08:17 PM
My thoughts exactly :)