Currently Being ModeratedMay 6, 2012 1:03 AM (in response to cadplan)
I had freezing issues too, starting with Snow `leopard. I concluded, after much research, that it was down to the nVidia 7300GT graphics chip in my machine.
I don't believe a fix will come - this has been evident for some time now, certainly enough time for a fix to be developed if it's going to be. I have read that the cause is an issue with some batches of the nVidia chip.
Interestingly, we bought 2 identical 24" 2006 iMacs at the same time - the other one has had no problems at all. That certainly supports the idea that it's a fault in hardware somewhere.
I found two things that helped:
1. I used SMC Fan Control (Google it) to keep the temperature down by managing fan speed
2. I found the issue much more prevalent in graphic-intensive applications, so I started using the other iMac for that.
Currently Being ModeratedMay 6, 2012 1:30 AM (in response to nick101)
My iMac, about the same vintage, running on Leopard has just started freezing. Touching the on/off button seems to release it, without losing what I'm working on.
Seems to happen when I'm using Safari.
Must admit I'm thiking I'm about due to upgrade, but I'm waiting for Lion to be released in UK.
Currently Being ModeratedMay 6, 2012 2:32 AM (in response to cadplan)
thanks for your replies, yes mine has the same graphics card. It only freezes in Vectorworks which is the CAD programme that i use daily. To be honest I'm just trying to keep it going until the new iMacs are launched which hopefully will be in the early part of the summer. I'll try the fan control although I've read that this is only a temp fix. I wonder how easy it is to buy and fit a new card?
Currently Being ModeratedMay 6, 2012 3:13 AM (in response to cadplan)
Fitting a new card isn't really an option - I explored this with a local Apple tech. The graphics chip is part of the motherboard, so replacing it means a new board - he reckoned the costs would be so high as to be poor value.
It's a disadvatnage of the all-in-one design, I suppose.
I sprung for a new 27" iMac 2 weeks ago - I edit video and process photos, and I couldn't manage with the freezing any more. I'd thought of waiting for the new iMacs but the expected date kept slipping and I realised that the current model had plenty of beef for my purposes. I added an extra 8GB memory (total of 12GB, and it flies. I just rebuilt an Aperture library with 13,000 images in it in about 7 minutes. Fabulous.
If you can manage with the issue for a few weeks, then waiting makes sens, sicne the new models will probably come in at the same price. If it's intolerable, then the current model will make you smile.
Currently Being ModeratedMay 6, 2012 4:45 AM (in response to nick101)
Yep I'm really looking forward to to the new model, I plan to get the SSD version and load it with RAM as well!
I think the cvard may be separate from the nboard, interestingly I found this web article www.techdc.com/imac-24-opened-and-upgraded
Currently Being ModeratedMay 6, 2012 6:07 AM (in response to nick101)
Although it is too late since you have purchased a new iMac, the information given you by the Apple tech was wrong. The 24in. iMac has either the Nvidia 7300GT video card or the BTO option Nvidia 7600GT video card which are both replaceable by either the Apple store or a certified Apple Care technician. The cost of either was approx. $350 either place. I know because I had mine done. The 21in iMac's video card was part of the logic board and thus was non-replaceable. I believe they had an ATI card.