iMac Freezing

I have the exactly same issue here with 1st gen iMac 24" and I think I've pinpointed the reason.

Everytime the GPU Diode temperature closes up to 50 degrees Celcius, the graphic glitches start to happen. At this point I have to use smcfancontrol to get fans up to speed and cool the diode down. And by that the glitches disappear around 45-47 degrees. If the temperature stays longer over 50, the comp crashes totally and has to be rebooted.

It's about 19 months old, gotten from the first patch arriving here and these problems started about 6 months ago. But I also have to work with the machine all the time and haven't been able to get it to be fixed yet. 😟

But I think the main reason is the GPU Diode, not sure which temp it's supposed to be, but at least mine can't do over 50 for sure. I see the issue directly related to that.

I use iStat pro to check the temps.

I concur with the post above. I also noticed that when the GPU reaches a certain temperature (about 140F) I start getting glitches, Im using SMC fan control, and if i see my temps start to rise, I just kick in the fans, by keeping the temp under 130F Iv'e been glitch and crash free.

Its still a bummer that this problem even exists and is so common. My Imac used to run so quiet, and i didnt have to be worrying about manual Temperature control. Apple should really do something about this.

Just a follow up that I have found the source of my problem - it is the external firewire hard drive (a Western Digital My Book). Since removing it completely I have not had a crash nor freeze nor had to shut down for 4 days. But when I plugged it in, did a Time Machine backup and left it plugged in things started hiccoughing. When Finder froze and a couple of other programmes as well I did not try and Force Quit them - I just pulled out the drive, which would not unmount. I got the Device Removal warning - but then about two mins later Finder and the other apps recovered.

I have been on to AppleCare and they suggested reformatting the drive because although it uses the appropriate format it has been formatted for PPC and this is an Intel iMac - they don't know that it will solve the issue but that is the next thing I will do.

Anyway, just FYI for anyone that stumbles on here with a freezing problem.

Deborah

So I took my imac in on sunday and I just got it back today. Now I have green showing up in my blacks in these usually vertical lines. very annoying. I just lost my computer that I need for classes for a week, and now I'm going to have to give it back for another week because I got another dud? The repair would have cost $1,900, the cost of the computer, without a warranty...ouch.

While I do agree that the cause of these kind of issues needs to be addressed by Apple and hopefully remedied. I am also a big advocate of using the Fan controller to help prevent these kinds of problems. However the bad news is if you are experiencing hardware induced crashing then the damage has already been done and no Firmware or software update is going to fix it. If still under warranty you need to have your machine serviced.

George

I'm another one with the same problem, helped to some degree by fancontrol - but still crashes if tries to play games eg x-plane. I like mac software but before buying a new imac (with applecare this time)is there anyone out there with an intel imac that has not developed a problem? Is this forum really for a minority who are unlucky or are most mac users likely to succumb?

I purchased my 24" iMac about a month ago. After a couple of weeks the hard drive died and was replaced at the Apple Store. I re-installed the Leopard 10.5.4 software and then restored my files using Time Machine.

Every time I turn on the computer it freezes. Sometimes, if I keep the mouse moving after the initial apple appears everything works fine (it took 4 tries for that to work this morning), but I shouldn't have to do this. I've read lots of the threads here, but they are older posts and don't seem exactly related to my problem. This only happens when I start up -- I don't have any problems at all once it's been running.

Any recent ideas/suggestions?

I just bought a new iMac 20 inch 2.66 GHZ Intel dual core computer yestertday. During the initial set up process the computer freezes up (I get the spinning color wheel). This usually occurs when I try to move from the "Transfer Data" page (which I choose the "Don't transfer" option) or when I try to do anything on the internet connection page including when choosing not to set up a connection at this time. The owners manual has absolutly no information. It basically says to just plug it in and let the computer do the rest so I'm not even sure why they bothered printing these up. So, to wrap things up, I can't even gain access to my system. This is just a little frustrating.

Is this a common problem for iMacs?. According to these discussion boards there seems to be a a generall feeling that the freezing issues is due to a graphics card issue. Do you think that's the problem?

I have been having the same exact issues as everyone else here so I brought my 24inch 2.16 in for repair. They replaced the video card and during the video diagnostic test at the Apple store they accidentally burnt an Image into the screen,Now I am waiting for them to replace the LCD...I will keep you posted on the results.

Add me to the list. My iMac 24 inch White began having problems with a Leopard upgrade. I first noticed that my Mac Mini's graphics are faster than my iMac on iPhoto cropping. Then the iMac began have horizontal lines on the screen, and some freezing. I suspected the nVidia 7300, but my son who is a Mac genius for apple says he believes it is software. It does seem that when I run in Windows, that I have not seen any of the problems... but then I haven't stressed it much in Windows.

I will try running my fan up with smcFanControl and monitoring the GPU temp with iStat Pro. I'll post what happens.

Bottom line here is that many people are having what appears to be the same problem, but Apple is unwilling to declare that there is one. I suspect that software may be exacerbating the problem, but that hardware is the root cause.

Add me to the list. My iMac 24 inch White began having problems with a Leopard upgrade. I first noticed that my Mac Mini's graphics are faster than my iMac on iPhoto cropping. Then the iMac began have horizontal lines on the screen, and some freezing. I suspected the nVidia 7300, but my son who is a Mac genius for apple says he believes it is software. It does seem that when I run in Windows, that I have not seen any of the problems... but then I haven't stressed it much in Windows.

I will try running my fan up with smcFanControl and monitoring the GPU temp with iStat Pro. I'll post what happens.

Bottom line here is that many people are having what appears to be the same problem, but Apple is unwilling to declare that there is one. I suspect that software may be exacerbating the problem, but that hardware is the root cause.

I have a brand new (bought in April, actually) 24" iMac Intel dual core 3.06 ghz model and have been having the freezing up issue, but not any of the graphics or display problems. The precursor to all my crashes is always a high tone, or whine, or high pitched noise that is hard to describe but it fades in and out and I know the computer is frozen when I hear it. The mouse still moves, but I can't click on anything.

What's worse, is that when I force it to quit by holding the power button down for a few seconds and then turn it back on, I hear the high tone again, and the hard drive can't seem to be accessed because I get the blinking question mark folder icon, meaning the system can't be found. I'm thinking this must be a hard drive problem, but don't know how I can prove the hard drive is acting up when this only randomly happens (usually, it happens when I wake the machine from sleep, but not always) and I cannot reproduce it on command to any local Apple Store (not that there is any near me and I hate to have to mail this entire computer in for repair).

I don't know if heat is the issue with this problem as well, but for the record, the iStat temps for my computer are around:

Hard Drive - 135°
CPU A - 108°
CPU A Heatsink - 108°
Airport Card - 103°
Ambient - 73°
GPU - 122°
GPU Heatsink - 119°

and the standard fan rates without using SMC controller or something similar are:

CPU Fan - 1202 rpm
Hard drive - 1199 rpm
Optical Drive - 698 rpm

Djaneb2...

I have the exact same issue and fix. I turn off the WD drive whenever the iMAC is hung up and it starts to work again.

I bought the WD drive to use all the time with Time Machine. Now what? Did you follow up on Applecare's suggestion to reformat that drive?

Mark

Add me to the list as well. I have a late 2006 model 24" Imac. Iv'e tried reistalling the OS several times, but cannot get it to start up. I've tried resetting the Pram and a whole host of other things. I'm very disappointed in Apple. I've been an Apple user for over 10 years and a dot mac subscriber. I've had 5 imacs and this is by far the worst. Thank goodness my Windows Vista machine is running so I can type this post.

Apple....if your out there listening....announce a formal recall!!!!

Update-Took 20" imac to Apple store Regents Street.
Asked them to replace the graphics card, and was told to find someone good at soldering as they only replace the entire logic board.
I didn't find him funny. But the onset of a cold winter here in London has allowed me to turn down the fans and keep it steady at 45c without the imac screen freezing.

Shame as I read here that people in America got the graphics card replaced for $150.

If anyone has had a similar repair done in the Uk, I'd love to know thanks, price etc 😉

Thank god for SMC