iMac Freezing

FanControl is working for me as well.

Bad news here ,after 3 days it happend again 2 times in a row, made them spin faster now but
it's a partial fix, works most of the time but..........summer is coming 8-)
Stable is something else. And let's not forget there's a reason for this bug somewhere.
We still need a proper firmware/software update from apple

grtz
Hurb

Did you happen to notice what the GPU diode temperature was?

no i didn't,
was a little surprised because running slightly faster fans was working for a few days. Then it happend again. Sinds then i turned them on a little bit more an now it's running steady sinds my last post.
I will begin monitor gpu temps and exact fan speed from now.

gr
Hurby

Same issue with my 20" Intel iMac (late 2006).

This may sound daft, but for some reason I noticed that the freeze often happened when changing from one app to another or minimising/maximising a window in the dock.

I had "genie effect" on, and since turning this off I get the graphical glitches far less frequently. Was running well for a few days then froze again. Running smcFanControl as weel now.

Much more stable now but I don't think it's entirely cured.

Another thread suggests it's an nvidia card problem but my machine's got ATI.

If you've got genie effect on try turning it off - may seem like a long shot but you never know.

Personally, while it may be a hardware issue, I've a funny feeling it's software related and that there's a memory leak or something erroneously writing to graphics RAM.

AC
AC

+1 with the same problem : glitches, strange pixels, freeze and eventually, black screen of death 😟

Mine was having the exact same problems. They all started after I updated to Leopard and the graphics update. Crazy pixels, sometimes a horizontal line then eventually it would freeze. The mouse would still work but the GUI was frozen.

Started using SMC Fan Control and that worked okay. Eventually it stopped working and it would just freeze all the time. Friday I came home from work and it was frozen. This time I couldn't restart it at all (it would just freeze). I tried to reinstall and it would keep freezing. I put it in target mode and transfered my stuff to another Mac.

The guy at the Apple store said they would cover the repair even though it wasn't under warranty! I think the reason is that this computer was an Apple Care replacement for a G5 lemon that I had.

Anyway, to make a long post longer... 🙂 I should get it back tomorrow and they are going to replace the graphics card and then stress test it for me.

I will post an update when I get it back.

Got my iMac back this afternoon. They replaced the graphics card for free. Been running for several hours and it has been flawless. I played some World Of Warcraft and it worked wonderfully! WOW would almost always freeze it up unless I maxed out the fans.

So far so good.

Youre completly right , this is a leopard/nvidia driver/software problem.

Shame they don't adress it.

gr
Hurby

Except that mine's got an ATI card...and is running Tiger

I still think it's software though

AC

Message was edited by: Alley_Cat

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

Since updating my first MacBook Pro (June 2007 model with Nvidia 8600M) to Leopard I have had frequent all out freezes on my system. These seem to be triggered by graphics apps. I also notice glitches and odd behavior at times during screensaver. I have not noticed the horizontal lines many of you, and this issue may be different than the one with iMacs, however it does happen daily.

The laptop is rather hot when it freezes, but hard to say if it's above normal. It is always well ventilated. Always connected during these freezes is an Apple 23" Cinema Display that spans with the built-in laptop monitor. After diagnostics checked out fine, I bought a new, identical laptop so i could actually get some work done. I reinstalled only core applications on this new computer, however it still freezes outright in the middle of light-duty work. Two identical laptops, one OS, same problem. I would like to point out that this issue never happened on the first laptop which shipped with Tiger. Only after upgrading to Leopard was it freezing constantly and forcing me to consider running BootCamp with Windows XP to get any real work done.

Does this remind anyone else of the System 7.5.X days? Constant crashing and freezing on a daily basis. Perhaps that's just a retro fad Apple is bringing back. Good luck to all of your with similar problems, I feel ya.

Same exact problem, posted about this a long time ago, took it to the apple store and they told me it's a problem in WoW. But it only happens on my iMac when it's hot, and only happened when I upgraded to Leopard. How do you install smcFancontrol on an imac?

http://discussions.apple.com/thread.jspa?threadID=1423776&tstart=0

Just wanted to add my name to the list of unhappy iMac Users. I am having the same problem on my late 2006 20" iMac. It also started after I installed Leopard. The frequency of the freezes seem to increase with time.