Horizontal Lines appear in random spots on display

Last night I downloaded smcFanControl and I am VERY happy to say that my iMac has gone 24hrs without any video problems, lockups, freezes, etc. I have a 20" iMac that is 24/7 hooked up to a 42" Sony LCD in Mirror Display so my graphics card works overtime.

Before installing smcFanControl, my temp was reading 125-140 degrees F, and is now running at a 'cool' 90-95 degrees F. I did not raise the fan speeds as high as some of the users in this discussion, but even ODD 1300, HDD 2200, and CPU 2000 settings were enough to solve all issues.

It is interesting though that not once in my conversations with Apple was it mentioned that it could be a hardware issue and that other users had reported these problems. It was only when I looked around Discussions did I see how many people were affected by this issue. The iMac has an incredible design and Apple keeps improving its looks...but at what cost to the functionality. I would rather have a 100% working system than fans that ran at inaudible speeds...

Thanks for the advice, saved me a lot of headaches and trouble!

I'm finding that sometimes I need more or less additional cooling. smcFanControl allows you to create different speed profile settings and save them. Currently I have created 25%, 50%, 75%, and 100% settings along with the original default setting. Having a temperature display and quick access to the different settings in the upper right menu bar has really made it easy to keep my system in a reasonable range. If I forget to pay attention, my display graciously reminds me by inserting random horizontal lines onto the screen.

A couple of other quick notes:
1. As a late arrival to the Mac party, I didn't realize that unplugging the chord from the Mac for 15 seconds is part of the system reset procedure. Its good to know that my superstitious suspicions are based on fact.
http://docs.info.apple.com/article.html?artnum=303446

2. For me fan noise on my iMac is not an issue. Unless I'm running it at full speed I barely even notice the fans. I've got a Dell sitting on my desk with fans that sound like a jake brake on a Peterbilt and run constantly. It has also had graphic chip cooling problems that I had to resolve by upgrading the fan. Between the Dell and two external backup drives that sound like jet engines every time they spin up, my iMac seems as silent as a hummingbird.

OK-

I have become so fed up with the lockups and display errors that I dismantled my 20" iMac and cleaned out all the dust from all 3 fans (there was some, but not enough to be worrisome.) It's back together and guess what? It STILL has errors.

I'm chasing it down now, it IS a driver issue. I downloaded the 10.4.9 combo update (that's right, TIGER drivers) and extracted the ATI drivers and replaced the current drivers on my system. So far, rock solid, no lines, and no OpenGL (have to work on that.) GPU runs in the upper 40 degree range, and computer feels fine.

If Leopard is so taxing on the hardware to cause overheating, then Apple needs to address it NOW. I should be able to use ALL of the cycles on my GPU for DAYS and not have an issue- as opposed to using Time Machine and having the 3D effects instantly cause glitches in my display.

If I come up with a fix that gets OpenGL running as well, I will post instructions here.

Scott.

Follow up: Turns out what was actually happening was Quartz Extreme was disabled using these drivers. I can get the same effect using the newest (Leopard Graphics Update) drivers and turning off QE.

Back at square 1. But, I know it is a problem with the driver. I am a very frustrated Apple customer.

I have not had a problem again except for the other day after a power outage. I knew it was scheduled, but forgot to turn off the computer so it shut down through my UPS. This always causes some problems on all the computers and it brought back the lines on the screen and slowness problems on the iMac. So, I shut down the computer, unplugged all cords and left the thing overnight. Next morning plugged it all back and since then no problems.

I have similar problems:, and an added one: random gradients.

weird distorsions


horizontal lines


random gradients


The weird thing is that in my Windows (I know, it's just that there are some programs I need...) when I start it up, it shows little colored spheres, so these makes me think this is not a software/driver thing...

Yeah, I've got all of those as well.

frikova wrote:
The weird thing is that in my Windows (I know, it's just that there are some programs I need...) when I start it up, it shows little colored spheres, so these makes me think this is not a software/driver thing...

Well, you have to remember that the ATi driver that gets installed in your Windows (I'm assuming you're using Boot Camp) is provided by Apple. If these problems are related to the latest drivers that come with Leopard, and those drivers are more or less the base for the Windows drivers that get installed via Boot Camp, then there's a good chance that they'll cause similar/same problems.


If nothing else, I've personally verified that this problem is almost absent when I boot my iMac into Tiger, which I think is a strong indication that the problem is software/driver related.



As a side note, I just had the chance (unfortunately) to do a complete clean install of Leopard (that is, an erase and install) for various reasons. I'm currently sitting next to a near virgin iMac with the latest update to everything, and with but a single application running (Activity Monitor), this problem is already rampant, displaying all of the graphical problems reported here (vertical and horizontal lines, distortions, gradients, smearing).

Yes, I'm using bootcamp.

My iMac has an Nvidia card, and I've tried even with the nvidia's drivers. Nothing changes. I agree that it should be something related to the software, hence these problems are screenshot-ables.

The SMC Fan control Works! Thanks so much guys. I had a 24" Nvidia 256VRAM Rev 1 iMac bought Christmas 06.
Exact same problems with the lines, freezing, and beach balls which got progressively worse. Graphic intensive games like COD 4 on XP under Bootcamp would heat up and I would get a memory dump. No issues for last two days, including on XP Side after running the SMC Fan Control. Tested under FCStudio2, Dreamweaver, Photoshop with some pretty heavy file action. The great thing about this SMC is that it works under XP on Bootcamp, as long as you boot over from the Mac side. Settings that worked for me: ODD 1263,
HDD 2214 CPU 2036
You saved me a trip to the Apple store for a replacement GPU it looks like. Apple missed the ball on the Rev 1 iMacs by not having better/faster fans. I can't talk about the aluminum 24", cuz I don't know.
-Chris

Well, I don't know about you guys, but I've pretty much decided this is definitely a driver issue.

I've been having all the problems people have described here, and I just confirmed, for the nth time, that if I boot into Tiger, the problems go away.

Unlike with many people, controlling the fan speed with SMCFanControl didn't do me much good. True, under 10.5.2., heat seems to play a role; however, increasing the fan speed to 2500 across the board, or even to 3000 rpms didn't get rid of all the artifacts.


This is on a Leopard system that I totally refreshed the other day for various reasons and thus is a near virgin-state system. BTW I did a complete erase and install of Leopard, and the very first boot into 10.5.0 displayed all the glitches now familiar to us.


So, today, I went and fetched my 10.4.7 disc that came with my iMac, used Pacifist to extract the following extensions in Essentials.pkg/System/Library/Extensions:

ATINDRV.kext
ATIRadeon.kext
ATIRadeonDVDDriver.bundle
ATIRadeonGA.plugin
ATIRadeonGLDriver.bundle
ATIRadeonX1000.kext
ATIRadeonX1000GA.plugin
ATIRadeonX1000GLDriver.bundle
ATIRadeonX1000VADriver.bundle

Then, just to be up-to-date as possible, I downloaded the 10.4.11 combo update for Intels and again using Pacifist, extracted System/Library/Extensions:

ATIRadeon.kext

and replaced it. If you want to do that, you could probably just skip installing that in the step above.


Reboot.

And, voila. No artifacts. And I have a nice and quiet system back again, which is nice. Sure, I don't have some of the nice graphic effects that requires QE or whatever, but those things mean jack when my screen is full of artifacts that are driving me near insanity :-p

I sure hope Apple/ATi/AMD can get their act together and fix this issue ASAP, but I won't be holding my breath. I may just go with this setup for a while to come.


FYI, as you may have guessed, my iMac has the X1600. If you have these problems with another card, you'd probably want to extract the appropriate drivers.

Hmm, one side-effect that's kind of annoying... I can't get Cover Flow to work in either the Finder or in iTunes... which is weird because, Cover Flow existed, at least for iTunes, before Leopard. That's one thing I'd like to figure out, although I would still prefer a Cover Flow-less system without the display glitches over the other option 😉

Yet again, I seem to have spoken too early. Cover Flow does work in Finder, but not in iTunes. Which is weird because Cover Flow in Tiger worked in iTunes but not in Finder! :-o

Well, I'll see what I can find out. In the mean time, it's been a few hours in my new setup without a single horizontal line, warped window, or random gradation 😉

Corrupted VRAM may cause distortions in screen generation, due to Quartz engine and its hardware acceleration. I found software which testing VRAM (unfortunetlly for Windows) and it says that my VRAM has some errors. I got the same sympthoms: horizontal lines, freezes, corruption in 3D applications. You can eliminate horizontal lines in Mail, Safari and other html based applications by removing Quartz Composer.webplugin from /Library/Internet Plug-Ins. But it doesn't eliminate the problem with corrupted VRAM.
greetings from Poland
Marek

Does the VRAM tester work in a VM + Windows environment? If so, I'd like to try it out.

No, only BootCamp.