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Apple Desktops Discussion of Apple's desktop machines including Mac Pro, iMac, Power Mac, and mini

iMac - 24" pre-Aluminum Intel-based: Severe screen tearing


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agarzola

 
Member Since: Oct 05, 2008
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Hello…

My iMac was purchased early 2007 and has worked like a charm ever since. Yesterday, though, I started getting some moderate to severe screen tearing. Today everything seems fine, except for a horizontal line that popped up on this very Firefox window I'm using right now, which disappeared after resizing the window a little bit.

I've run memory tests with Rember and my memory seems to be fine. I'm wondering if it's a video card issue, or a video card *driver* issue.

A factor to consider is that this machine has been known to run non-stop for months. It is my main machine and I use it for all my design work, and I leave it on during the day to access files on it from the studio where I work during the day. So it may be that those extremely long periods without rest have had adverse effects on my hardware…

Anybody who has seen this before and could give me a clue as to what may be causing this, I'll be very grateful.
Attached Images
File Type: jpg tear_1.jpg (277.9 KB, 27 views)
File Type: jpg tear_2.jpg (752.2 KB, 28 views)
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macgig

 
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Mac Specs: 20" 2007 Aluminum iMac 2.0 Ghz | 4 gigs ram | 10.6.8

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never seen it before but my first thought is a video card issue. create a test user account and see if it happens while using that account. If the problem does not occur with the test account, you can focus on things that are user specific, such as permissions and preferences.
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agarzola

 
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Thank you, macgig. I'll do just that and hope to report here with the results sometime tomorrow.
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harryb2448

 
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Also you should have Apple Hardware Test on the system restore DVD. Give that a run as it does check graphics.
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Chilbear

 
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Mac Specs: 2xiMac24 w Parallels 6 (1x White, 1x Aluminum), iPhone 3GS with iOS5

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My 24 Aluminum screen went wonky after the last update on Thursday past. Would not respond and the screen had horizontal oddities. I force it off with the power button and waited 30 seconds and restarted. All is well. Hmmmm...
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agarzola

 
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Thought I'd give an update…

Shortly after macgig posted his/her suggestion, I created a test account and logged into it immediately, using fast user switching. The iMac *did not* like that. The entire dock was a big mess of seemingly random pixels (not too different from the messed up areas of the screenshots above), and a Finder window would only move smoothly if I kept it away from the lower quarter of the screen. As soon as I moved the window closer to the bottom of the screen (near the dock), it would start lagging severely, until I moved it back up. This makes me think that it may have had something to do with the reflection that shows on Leopard's Dock surface when windows move close to it. So, I'm inclined to think it's a video card problem, indeed.

Anyway, when I logged out of the test user account, the screen went blue (the same hue as one would get behing the login screen in previous versions of OS X) and that's when it beachballed indefinitely. Ten minutes later, I had to force shutdown the computer. After turning it back on, everything seemed smooth again (as it usually does, at first) and so I left SoftRAID take care of some rebuilding it had to do while I left the apartment for a few hours. I returned about six hours later to find the computer still in good shape (perfectly responsive, no lagging or tearing), and I thought I'd give it a test run.

I worked on a small job I had to get done by tomorrow, using Photoshop, Illustrator and InDesign (all CS3), with Linotype FontExplorer X, SoftRAID and Transmission all running in the background (as well as Quicksilver, ted and Plaxo). Use of Photoshop included scanning some medium-sized images, I did some live tracing in Illustrator and handled a few large TIFFs requiring high quality previews on InDesign. The computer has remained very responsive, with no lagging or tearing whatsoever. I finished the job, generated the final files and sent them to my MacBook over my LAN to send to the client over email later on (Mail on my iMac has been buggy ever since the Leopard upgrade… another issue I've yet to figure out).

All seems to be well for now, and the iMac will remain turned on for the rest of the night while SoftRAID finishes rebuilding some disks. I'll report back here as soon as I have news.

harryb2448: Thanks for the tip! I'll certainly look into that if I run into further problems. Although, perhaps I should run that hardware test regardless. Either way, I'll make sure to report it here.
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