Request help on freezing early 2008 iMac (24 inch)

[ViennaMac]

Greetings:

Thank you in advance for any assistance/ideas/referral to threads. I have an early 2008 Imac which suddenly in May 2013 began freezing. Usually force quit does not resolve the problem.

Symptoms: Screen almost always flickers several times then freezes, we can move the mouse, we can usually hear audio, and every now and then we can force quit (but almost never) and resume normal ops. We are not taxing the machine. We are not "power users". SImply watching netflix can induce this.

What I've done:
May 2013 - Replace hard drive (first visit to Mac store per their recommendation)= did not resolve issue; froze immediately when taken home. I added additional RAM (from 2 to 4 both seated properly).

July 2013- Replace video card per their recommendation (and strangely a failed hard drive fan even though this had also been discovered as failing during the first visit)= within 1 day home the computer froze again while only netflix was running a cartoon for my child. Strangely now also our fan is ridiculously loud.

Any thoughts/ideas/comments are welcome. Everything passed the Mac store's tests. Please let me know if supplying more info would help.

Thank youVM

 

[50548]

My first bet would be the GFX card, but you have replaced it already - something in the MOBO perhaps?

Otherwise, have you tried wiping the computer and reinstalling the OS again?

 

[JackRM]

early 24" iMacs does not likes heat.
And watching full screen movies means heat for 24" A1225 iMac.
What graphic card you got ? NVidia 8800?
Your fan is loud because your iMac runs hot / or last time they did not connect the temp sensor to your hard disk.

 

[Brian33]

I don't agree with the above as being the problem. I have a 24" Alu iMac 8,1 "Early 2008" with a similar problem and have read extensively about it.

We'd need to know more info about your iMac, but it sounds like the same problem I've encountered and is discussed (for over 90 pages) starting here:
https://discussions.apple.com/thread/2384136?start=0&tstart=0

The gist is, for certain models of iMacs with certain graphics cards, use of the ATI graphics drivers ("kext files") after OS X 10.6.2 can cause various screen artifacts and "screen freezes" (but not audio freezes), where no mouse or keyboard input will do anything. Changing the graphics "kext files" back to the version from OS X 10.6.2 fixes the problem for many, and the old kext files work fine at least through 10.8 (i.e., there don't seem to be any conflicts or bad effects from user the older drivers).

There's a lot of talk about heat issues causing the problem and using fan control programs, but my reading and experience has convinced me that heat and/or fan issues are not the cause of this particular "screen freeze". Using the older kext drivers has returned my iMac to usefulness.

I'm going by memory now (you can read the thread), but I believe this solution worked for iMac 7,1 and iMac 8,1 machines with ATI video cards (not for NVidia cards).

You can click ->About This Mac->More Info and look under Model Identifier to help you know if this solution might help. Also look up your graphics card info under Graphics/Displays. (I'm still on 10.6.8 so might be slightly different if you're on Lion or Mt. Lion.)

So, I'm curious to know, what Model Identifier do you have and what's your graphics card model?

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Oh, and if after some thought think you do have the same problem as I and many others, here's a web page by the guy who first figured out the solution (beloved by many!) showing how to install the older graphics drivers for ATI cards:
http://blog.krzysztof-turek.com/apple-imac-8-1-freeze-problem-solution-en/

 

[Sped]

I'd bet the graphics card is dead again. Perhaps the replacement wasn't performing well?