iMac display corruption

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iMac display corruption

Postposted on Wed Nov 12, 2008 4:11 pm

One of my users has an aluminum/glass iMac (8,1) with Radeon 2400 video. For a couple weeks now the display will eventually dissolve in static[1]; the wallpaper largely disappears and so do some of the icons, but when you move the mouse pointer around the screen returns to normal under where the pointer goes, likewise if you click-and-drag on the desktop to make a box.

He took the Mac to a repair depot, where they replaced the motherboard, video card, inverter, and something else. The tech asked me to do an archive-and-install of 10.5 to flush out the old video driver, in case that was corrupted. I did so, didn't have any problems for a couple days while it was getting set up and updated. After the user had it for about that long, the static came back. On a hunch I ran a program to check the temperature sensors, but nothing was unreasonably hot; 50 Celsius was the hottest for any of them.

Any ideas?



[1] Non-moving static; my user describes it as "plaid".
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bthylafh
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Re: iMac display corruption

Postposted on Wed Nov 12, 2008 4:21 pm

Sounds like a program the user is running might be corrupting the video driver. Anything unusual they're running that might tax the video driver like CAD or visualization apps? Can you clone their hard drive to another machine of the same model and see if the pattern travels to that machine?
bdwilcox
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Re: iMac display corruption

Postposted on Wed Nov 12, 2008 4:29 pm

I'll check his account to see if he's got anything odd running on login. That would make sense, since I was having no trouble when logged on as myself.
Think for yourself, schmuck!
i5-2500K@4.3|Asus P8P67-LE|8GB DDR3-1600|Powercolor R7850 2G|1.5TB 7200.11|1988 Model M|Saitek X-45 & P880|Logitech MX 518|Dell 2209WA|Sennheiser PC151|Asus Xonar DX
bthylafh
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Re: iMac display corruption

Postposted on Wed Nov 12, 2008 4:44 pm

The only thing that ever screwed up the display on my iMac was when I ran Shades or a similar app to dim the screen. It's a long shot, but look for an app like that and see if the user runs it.
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Alex
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