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User profile for user: PrimaryFeather
PrimaryFeather Author
User level: Level 1
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iMac 2007 (20 inch) - Moiré Pattern in Mavericks

Since I upgraded to OS X Mavericks, I see an annoying Moiré pattern on the display. The effect is visible only for certain shades of gray; it looks like a wave that moves over that region of color.


I tried to capture it on video. Here is a sample:

https://www.youtube.com/watch?v=qi-tw40NrbY


You have to view it in HD to see the effect. It's the wave that's visible in the region right next to the "No description given" text. Unfortunately, Google's video compression removed some of it's visibility; in reality, it's much better to see and affects the complete region behind the text. Very annoying. :-(


Any ideas on a cause, or what to do against it?

Thanks a lot in advance!

iMac (20-inch Mid 2007), OS X Mavericks (10.9)

Posted on Oct 27, 2013 11:31 AM

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9 replies
User profile for user: Delgadoh
Delgadoh
User level: Level 4
1,481 points

Oct 29, 2013 11:40 AM in response to PrimaryFeather

Hey PrimaryFeather,


I would start with resetting the Mac's parameter RAM and SMC:


Resetting NVRAM / PRAM

  1. Shut down your Mac.
  2. Locate the following keys on the keyboard: Command (⌘), Option, P, and R. You will need to hold these keys down simultaneously in step 4.
  3. Turn on the computer.
  4. Press and hold the Command-Option-P-R keys before the gray screen appears.
  5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.
  6. Release the keys.


Resetting the SMC for Mac Pro, Intel-based iMac, Intel-based Mac mini, or Intel-based Xserve

  1. Shut down the computer.
  2. Unplug the computer's power cord.
  3. Wait fifteen seconds.
  4. Attach the computer's power cord.
  5. Wait five seconds, then press the power button to turn on the computer.


via: Apple computers: Troubleshooting issues with video on internal or external displays

http://support.apple.com/kb/HT1573


Have a good one,

Delgadoh

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User profile for user: Swasster
Swasster
User level: Level 1
0 points

Dec 2, 2013 8:10 PM in response to PrimaryFeather

I am having the same issue with my '07 iMac 20".


I have a feeling that the problem lies within the driver and that it is reducing the visible colors to the old '80s 1028 colors due to either the fact that the graphics card has a lower than preferable amount of memory or some similar reason.


It's like I need to deguass my screen again. But wait, this isn't a CRT. You know what I mean. I hope Apple fixes this issue. I am sure they will.

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iMac 2007 (20 inch) - Moiré Pattern in Mavericks

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