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abenamou

macrumors newbie
Original poster
Apr 29, 2015
5
0
Not sure if anyone else has run into this. I returned my first iMac 5k (4ghz/295x) because of the issue, but the replacement does the same thing. Apple phone support has never heard of the issue.

When moving windows around the screen, the drawing is best described as "tearing" like where the contents of the window trail the window by a few milliseconds. Additionally the window contents seem to have corruption in drawing while moving (the window gets broken into blocks which move around). It all corrects itself once the window stops moving.

Rebooting usually clears it up but it returns. My first iMac it came back within minutes. The replacement ran about 12 hours before doing it again. The only app running is Chrome with about 15 tabs open or so. This is running the latest OSX with all the patches, etc.

Hard to believe it's a hardware issue now (originally it looked like bad VRAM to me). Anyone else see this?
 
Not sure if anyone else has run into this. I returned my first iMac 5k (4ghz/295x) because of the issue, but the replacement does the same thing. Apple phone support has never heard of the issue.

When moving windows around the screen, the drawing is best described as "tearing" like where the contents of the window trail the window by a few milliseconds. Additionally the window contents seem to have corruption in drawing while moving (the window gets broken into blocks which move around). It all corrects itself once the window stops moving.

Rebooting usually clears it up but it returns. My first iMac it came back within minutes. The replacement ran about 12 hours before doing it again. The only app running is Chrome with about 15 tabs open or so. This is running the latest OSX with all the patches, etc.

Hard to believe it's a hardware issue now (originally it looked like bad VRAM to me). Anyone else see this?

Never heard of this happening, either. Can you post a video of it happening?
 
Uploaded the video, waiting for the post to be approved. I noticed this happens only when the resolution is set to "best for display". Oddly switching to anything else and the problem goes away.
 
So, this only happens when you are using Chrome?
That may help you decide that Chrome is just not the best behaving software in the world of browsers.
Have you tried some other browser - maybe Safari/Firefox/Opera/Webkit, or one of the other dozen or so browsers that often are more CPU/RAM friendly than Chrome?
 
Sorry if that wasn't clear - it's not Chrome related (yes it can be a pig). It happens with even system dialogs and any window really. So like the control applet, finder, etc.

What it seems like is once the VRAM gets "full" by running some apps, then it starts to mis-behave. I had the Apple Photos app open and it started happening - and when it does any window you drag is affected.
 
Thanks for the suggestion, it all reports as normal. Since I had two identical systems with the same issue it leads me to believe it's a software issue.

What is strange is selecting a different scaled resolution solves the issue, but putting back to "best for display" and it reappears - until a reboot where it works for a while.
 
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