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TheNewFlesh Author

Level 1

0 points

Horizontal Lines appear in random spots on display

Hey everyone.

Recently, my white iMac has been locking up a lot lately (forcing me to hard-reset, boo) and horizontal lines have been appearing. It freezes most often during more graphically-intense applications like games and Pro Tools. It's not the regular Mac freeze, where the grey dialogue box politely and multi-ligual-ly informs you that you need to reset. When my computer freezes, things just lock up, or the screen will go black.

I thought since I had not done a whole lot of computer maintenance since I bought it, there was a possibility it was just a horrible software glitch.

So I zero'd my hard drive and reformatted. Almost immediately the lines returned. Interestingly enough, I don't need a digital camera because these awful lines can get captured by screenshots.

The lines are typically pinkish or black, but if you look close, the individual pixels in the lines seem to be coloured arbitrarily. If the lines appear on a window, I can drag it around and the lines will follow. If I resize the window, the lines disappear.

Here's a screenshot. Note how the lines only affect the one window, and do not span the entire screen.
http://img161.imagevenue.com/img.php?image=29918lines_122708lo.jpg

These lines aren't bound to a particular window, just the desktop as a whole.
http://img142.imagevenue.com/img.php?image=45631lines2_1221119lo.jpg

How are these things getting captured on screenshot if I just reformatted my computer?
If it's not a software error, could a worn-out graphics card produce odd artifacts that are screen-capture-able? Apple ships hardware that can't last 2 years? Am I going to get shafted if I try to call them? Is there possibly a fix for this?

Thank you everyone for taking the time to read my post, and thanks in advance if you have some advice or want to express that you share the same issues.

2Ghz Intel Core Duo 20" White iMac, Mac OS X (10.4.9)

Posted on Dec 29, 2007 12:31 AM

115 replies

Dec 24, 2009 9:51 PM in response to Luke Noel-Storr

I've got this problem as well on my 2.16 GHz Intel Core 2 Duo. Smc helped for a while, but now the horizontal lines are back with a vengeance, even with the machine running at 26 degrees C.

Doesn't seem to be temperature - or at least not temperature alone - that was causing the problem.

Akjim

Level 1

0 points

Jan 13, 2010 7:04 PM in response to TheNewFlesh

I have had the horizontal tearing issues for the last 6 months or so but have no warranty. I went through the SMC fan control solution and it helped for a while, but every other session on the iMac results in horizontal lines or lockup ( black screen) or lock up with mouse control requiring hard restart.
I loved the computer and was an apple advocate but now I tell people about this when they ask about my apple...any real solutions would be appreciated.

Jan 16, 2010 8:58 AM in response to TheNewFlesh

ok ok ok. Me too. All the same problems. Most recently I weather stripped the windows in my wife's office and the problems escalated to a point of inoperability. I had suspected heat for a long time - cause the problems would occur at night while watching TV on the mac. But after reading this thread, weather stripping the office and buying (YES BUYING) a new iMac27 finally brought me here. 4 Macs, 2 iPhones, 4 iPods and and all I have now is 5 nasty words for Apple (I love your stuff LESS) today. I have a mind to return the new iMac27 and will sit on it for 24 hours as to not act too rashly. And yes - installed smcFanControl and can hear the fans for the first time. Temperature has dropped from 105F to 79F since installation 30 minutes ago. The theories about Bluetooth mice and boards seems possible and clearly graphic intensive operations TV and iPhoto all contribute. But for me it was the warmer room caused by the weather stripping on the windows that cemented deal. Seem our iMac was under the basement window and had fresh air until I fixed the problem - so to speak. Unrelated problem of not being able to install Snow Leopard on this machine for some reason - 'Snow Leopard can't be installed on this computer'. Tried 3-4 different approaches and still wont' work.

Jan 20, 2010 8:41 PM in response to Part time sysadm

I'm keeping the iMac27 and certain that I still have heat related problems with this iMac24. Hung for me this evening - even after successfully installing Snow Leopard. I'm thinking this machine is only good for email and a few other things - perhaps I'll give it to the kids. And to the folks at Apple-you really need to confess what you know about this problem. I have mac in my attic that were more reliable that this one. If a car manufacturer had this type of problem they would be forced to recall it.

TMeck

Level 1

0 points

Mar 25, 2010 1:28 PM in response to TheNewFlesh

Same Problem, Definitely started after installing Snow Leopard... Here's something I can offer that others have touched on the subject of heat. I have 5 iMac's in the same office with the same hardware/software configs and all have the Latest updates and firmware....Only 2 of them have this problem. Same temp/environment as the others so I'm not thinking that is it, also it's not "just" showing up on the display as it shows up on screen captures as well as QT movies if it happens while exporting from FCP? Had a Hard drive fail in one of the 2 with the problem and used the opportunity to start from scratch with the rebuild... Same thing once it was back up and running again???

MacLoyal

Level 2

259 points

Apr 18, 2010 8:00 PM in response to TMeck

This is happening to me with my MacPro, 6 months out of my APP on a mostly rebuilt computer. I'm having lines and screen freezes. I'm also having some bizarre behaviors with my menu bar at the top. Just the other night I opened Aperture and the menu continued to show Finder values. I had to click across each word and then into the blank spaces to the right one by one to get the menu for Aperture to appear. I hadn't connected all these strange behaviors before reading this thread. I wish someone had posted a definitive answer to what's going wrong here.

Apr 24, 2010 6:39 AM in response to TheNewFlesh

Same story as everyone else here, but with a happy ending.

After a long time limping along trying to get things cooled down with SMC Control, the iMac started glitching and freezing almost immediately after startup. It seems that once the graphics chip starts glitching like that, it's the heat sink that takes the battering. It's a matter of time until the machine is bricked.

I took mine in to http://applerepairsinlondon.co.uk and asked them to fix the chip. They claim to fix component parts of the logic board, rather than replacing the whole thing. They rang the next day to say that they'd need to do the heat sink too as it was pretty much gone.

Excited, I went in to pick it up, only to find that it was displaying pretty much the same problems. They said it was because of dead pixels and I'd have to replace the screen. Bollocks, I said.

I gave them another day to think about it, and they replaced the cable that connects the logic board to the screen and voilà, no more glitches.

All-in-all £250. Not too bad.

Jokul

Level 1

0 points

May 4, 2010 3:37 PM in response to TheNewFlesh

My iMac Late2006 have same problem recently. That really feak me out!
I used Fan control, but it doesn't work. I may need to replace the 7300GT card sometime.

May 12, 2010 8:49 PM in response to Brian Ibbott

Brian Ibbott wrote:
It's not just happening with iMac, either - it's happening on my 2006 2.33GHz Intel Core Duo MacBook Pro. EXACTLY like the photos below, with the 3D warping, random lines and instant black shutdown.

Exact same problem. When it got to instant black screen, though the machine was dead until it rebooted fine. Corruption was also visible on login desktop (horizontal line). Assumed it was a RAM error, but it wasn't. Followed usual procedure for debugging hardware vs software. Safe boot seemed to fix it. Tried several other fixes (cache cleaning, removing old kexts, etc) , since I didn't want to have to do an archive and install. No luck. Next presumed that it was a corrupted prefs file. Seems to be fixed on renaming /Library/Preferences/loginwindow.plist which then generates a clean copy on reboot. When looking for corrupt prefs files, I prefer to rename them as .dudyyyymmdd rather thna deleting, so if they turn out to be OK< I can restore previous settings.

May 15, 2010 1:36 AM in response to Ian Cheong

UPDATE:
Problem still not fixed. Improved but still there less severe - horizontal lines across some windows intermittently. Back to the drawing board....

May 17, 2010 9:57 PM in response to Ian Cheong

Problem seems to have resolved - not sure exactly what fixed it. Certainly the problem was not ever there on safe boot. Some times it would appear on login desktop and sometimes not.

The last thing I tried that seemed to fix it was an aborted attempt at archive and install (not enough disc space) that included changing the startup disc preference. So possibly it was a corrupt startup disk preference setting? I do think whatever was corrupt corrupted other preferences too, since rebuilding others partially fixed the problem along the way.

Other things that may possibly have helped along the way in reverse order of what I tried:
* run applejack in single user mode to clean out the system (<cmd>- to start single user; $ applejack)
See http://applejack.sourceforge.net/
* rebuild /Library/Preferences/SystemConfiguration (drag Library/Preferences/SystemConfiguration to desktop and restart)
* rebuild /Library/Preferences/com.apple.loginwindow.plist
* rebuild /Library/Preferences/com.apple.windowserver.plist
* followed various instructions "Mac OS X: How to troubleshoot a software issue" at http://support.apple.com/kb/ht1199
Good luck!

May 17, 2010 10:01 PM in response to Ian Cheong

Sorry... everything after <cmd> got redlined by mistake and posts can't be edited. : (

Should read:
Other things that may possibly have helped along the way in reverse order of what I tried:
* run applejack in single user mode to clean out the system (<cmd-s> to start single user; $ applejack)
See http://applejack.sourceforge.net/
* rebuild /Library/Preferences/SystemConfiguration (drag Library/Preferences/SystemConfiguration to desktop and restart)
* rebuild /Library/Preferences/com.apple.loginwindow.plist
* rebuild /Library/Preferences/com.apple.windowserver.plist
* followed various instructions "Mac OS X: How to troubleshoot a software issue" at http://support.apple.com/kb/ht1199

Good luck!

Jun 16, 2010 2:06 AM in response to Phil Gribbon

DbGecko I am amazed that you have a good story about apple repairs in London, i have read countless tales of peoples computers going missing, or being damaged by this terrible company. I am a victim of the con that they pull having sent my white macbook to be repaired, they went back on their original price and gave me a much higer one that i couldn't afford. The macbook that they returned to me was black,had no harddrive, and only 1gb of ram.
Personally, i would avoid applerepairsinlondon.co.uk like the plague.

Jokul

Level 1

0 points

Jul 5, 2010 12:17 PM in response to Olivercarding

After failure to fix this problem using software, I bought a new video card. I took 20 minutes to replaced the card by myself. Finally this problem disappeared. This problem can not be fixed by controlling temperature of iMac.

Jul 7, 2010 6:12 AM in response to TheNewFlesh

I just posted another message before seeing this thread. I'm having the same problem. The more graphic intensive the program - Google Earth expecially - the more noticeable the disruption. In Google Earth large areas of the display and sometimes the whole window are corrupted. It seems like this is a major ongoing issue for Mac. I hope Apple address it soon.

Horizontal Lines appear in random spots on display