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Level 1

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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

Apr 30, 2008 11:01 AM in response to MarekSz

That's what I figured. Well, I thing there was a way to install Windows on an external HDD and use that with Bootcamp... if I can figure out how to do that, I'll try to test it. Can you tell me the name of the app?

In the mean time, still going on without a single glitch in OSX 10.5.2 w/Tiger ATi drivers 😉

MarekSz

Level 1

0 points

Apr 30, 2008 11:19 AM in response to Satoru Murata

It's Video.Memory.Stress.Test. It's url from polish IDG site.
http://www.idg.pl/ftp/pc_16943/Video.Memory.Stress.Test.0.11b.html
Click button "Pobierz" (Download in polish). Write here the result of test, please.

Apr 30, 2008 1:32 PM in response to TheNewFlesh

Anybody try installing the Leopard Graphics Update very recently released by Apple? (i.e., like, today?)

I'm wary of installing it just to find out that it doesn't improve anything and then I'd have to go through the process of extracting drivers from Tiger again....

Apr 30, 2008 2:41 PM in response to Satoru Murata

Argh. Forget this stupid post. The update is the same thing we all downloaded in Feb. It just showed up on my iMac because I'd installed the Tiger drivers....

May 2, 2008 6:25 AM in response to TheNewFlesh

OK, here's the results after a couple days. True, with the Tiger drivers, I wasn't seeing the horizontal lines, the gradations, and other artifacts. But then I noticed that there were many, many little defects that looked exactly like dead pixels.

Then, I noticed that I had the same artifacts on my secondary external Dell monitor, at which point I was like (OK, this isn't dead pixels).

So, I swapped the drivers again to the Leopard ones, and the usual artifacts were back with a vengeance. I mean like really, really bad, it made the computer unusable until I turned SMCfancontrol up to like 3000rpm on all three settings. Apparently, heat was building up on the graphics card even while I was using the Tiger drivers.

Anyway, it was so bad that I took it into a nearby Apple Store, and they said it would require a logic board replacement. Me being really dumb, I'd forgotten to get Apple Care for this iMac (I always buy Apple Care, I just let the 1yr date slip with this one), and they'd charge me at least $800.

Obviously, I'm not going to pay $800 to fix something that I can buy a new one for $1000.

Sigh.

hickups

Level 1

5 points

May 5, 2008 1:16 PM in response to TheNewFlesh

SMC Fan control worked perfectly for me as well, I had TONS of problems with my computer grey screening and those stinking horizontal lines. One boot up after I installed SMC fan control and upped the RPM my iMac was back to normal. Wish I knew this before I formatted my hard drive.

IN SHORT, DOWNLOAD SMC FAN CONROL AND UP THE SPEED OF YOUR FANS.

May 7, 2008 4:27 AM in response to hickups

Thanks, SMC Fan Control solved the issues for me too (fingers crossed).

In addition to the problems mentioned above, I also had a couple of pixels that looked like dead pixels coloured magenta; however, sometimes when I moved a window around the screen the dead pixels left trails, as if they were drawing over the window as it moved past them. This could also be captured in a screen grab, showing they weren't really dead pixels at all.

May 10, 2008 11:59 PM in response to Luke Noel-Storr

Well the thing is, you shouldn't need SMCfancontrol. Most people don't have this problem without having to turn up their fans.

I've given up. I went ahead and bought a new iMac (refurb 2007 model). Not like this model is supposed to be flawless, but I bought Apple Care with it, and will aggressively pursue perfection from Apple this time around. At least for the next 3 years 😉

I have one final advice for people with this issue. I am now 100% positive that this IS a hardware issue. It's a faulty graphics chip, or something on the M/B. Seems a lot of saw this issue with the installation of Leopard. That just might be because Leopard is more taxing and so it kicked off the onset of the problem, but at least for me, it gradually got worse, and in the end, it was bad enough that I saw the EXACT same glitches even after I did a complete erase & fresh install of Tiger.

So, for those of you who are still in your warranty (either 1 yr or Apple Care extended): go to Apple immediately and get a motherboard swap asap. I will guarantee you that it will NOT get better with 10.5.3 or 10.5.4 or even 10.6 (Ocelot).

MarekSz

Level 1

0 points

May 11, 2008 12:28 AM in response to Satoru Murata

Last weekend I "improved" my iMac with two additional radiators on video memory chips.
I also installed program Fan Control. So far so good... No lines, no freezes 🙂

Yeehaa

Level 1

0 points

May 11, 2008 7:03 AM in response to Satoru Murata

Hmmm... I'm not quite sure. In my case, the fans never went up automatically anymore after installing 10.5. Therefore, it seems to be a software issue rather than a hardware issue to me. Also the fact that Remote Desktop (and Back to my Mac) shows the same artifacts when I connect to my iMac from another computer, seems to indicate that it is at least partly a software rather than a pure hardware issue.

Of course, when the computer has to endure excessive heat for an extensive period, irreversible damage could occur…

The big difference between Tiger and Leopard, is that the latter turns on Quartz 2D Extreme (QuartzGL) by default, which is more taxing to the graphics card. In my opinion, Apple seems to have miscalculated the fan levels for the processor / graphics card in Leopard… A system update should be able to correct that.

In any case, why did not Apple reply to this problem? Based on the number of responses on this forum, it seems to occur very regularly…

Message was edited by: Yeehaa

May 11, 2008 7:18 AM in response to Yeehaa

Yeehaa wrote:
Also the fact that Remote Desktop (and Back to my Mac) shows the same artifacts when I connect to my iMac from another computer, seems to indicate that it is at least partly a software rather than a pure hardware issue.

That might be simply because OS X uses the graphics card to draw a lot of stuff (like Core Animation) as opposed to doing all the drawing with the main CPU and merely passing that along to the graphics card for output.

I don't doubt that Leopard played a part in this, but as I said, I do not think it's reversible. Going back to Tiger didn't get rid of the problem.

simnie

Level 1

0 points

May 20, 2008 5:54 AM in response to TheNewFlesh

I updated to Leopard some time back - I don't remember exactly when. My iMac is from November 2006. 24".

Sunday the 11th while playing World of Warcraft horizontal lines appeared on my screen and the computer froze. I did a reboot but this time I did not even get a login screen.

I tried booting into Vista. Howeveer Vista shut down immediately after boot with a message telling me the system was shut down due to hardware failure.

I ran the repair/diagnostic tools from the OS X install CD1. No error was reported from the normal or the extended check. But the system refused to boot still. I did a ram reset (I don't remember the key combo). It did not help.

I managed to get the computer started and OS X to show a loging screen by doing a safe boot. The lines were still there. I left the computer turned on for a couple of hours and the lines disappeared.

I then decided too boot normally and run World of Warcraft again. After a couple of minutes the lines came back and the system froze. This time however I was unable to boot in safe mode. I tried a few times and suddenly it came back - with the lines.

I've spoken to Apple Support abot the issue but appearantly it's not a known issue. I wonder how that can be - judging from the responses here.

Currently my computer is being repaired and I fully expect Apple to pay for it. I Denmark warrenty for factory errors (which this one classifies as) is 24 months.

Quite frankly I expected better quality from Apple. I've been a PC user since mid 90s until November 2006 and I never had any hardware issues.

Jun 14, 2008 11:23 AM in response to simnie

Same issues here on a 24" iMac, late 2006 when running Leopard 10.5.3. SmcFanControl helps a lot.

I transferred my files from my old iMac over to this machine. I had wondered if the system didn't get transferred over right, but this board has relieved me. I'm not alone!

However... here is the result of my permission repair... Any comments?

Jun 20, 2008 6:41 AM in response to Journeyguy

I have been going nuts with random lines freezes ect and did Hardware test and this is the first time I have ever heard a fan on my iMac and the dust flew out of it !
I had previously checked repaired all permissions a few minor errors fixed but still problems Photo booth was black screen Apple said bring it in with your wallet as I had not bought extended warranty as having had Macs since the beginning had NEVER had a problem till now
was not looking forward to a reinstall of system and glad I did not after reading from others who did and no improvement
I have installed SMC Fan control the reading was 44 degrees centigrade at time of install I have no idea if this is too hot but will see how I go over the next few days .......now running 35 degrees after 10 mins
many thanks to list and PLEASE APPLE READ ISSUES THAT WE HAVE

Jun 22, 2008 7:42 PM in response to ponysoldier

As a dissaffected iMac owner, I'm just going to briefly comment, so that Apple sees this thread.

Horizontal Lines appear in random spots on display