Some kind of cooling problem or logic board?

Hi, I'll try to describe my problem...

when I sart up the mac, the boot goes well up 'till the grey apple logo when the "hold wheel" freezes.

If I try to boot the mac for 3 or 4 times in a row, the monitor starts to display lines and dots randomly.

At the fifth or sixt boot the lines and dots get worse.

If I try to boot after few hours... no lines or dots...

I opened the case and I can tell that the CPU heat sink was quite hot... but I heard the buzz of the CPU heat sink fan.

What do you think?


sorry for my bad english...

Answered! View the answer I have this problem too

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It sounds like the capacitors on your iMac are failing. These model iMacs are known for having the issues that you are describing. I recommend opening up the iMac and checking the capacitors, you may find that there are capacitors that are either beginning to expand at the top of them or that they have exploded. There are kits that are sold online to replace the capacitors but given the age and work involved, I don't think its a good idea, unless of course you have the time and want to take on a project! Search around for "iMac G5 capacitor replacement" for more info on that. Hope this helps!

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WoW, thanks a lot for your advice!

I'll let you know once I opened it up!

BTW, do you find possible that the thermal paste for the CPU/GPU has faild?

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Hi ACP, I've opened the iMac and all the capacitors looks fine... All the tops are flat and intact with no expansion or damages. I would have posted a picture, but I think I can't... Where do you suggest me to go from now? Change 'em all or try to investigate somewhere else? Thanks a lot!!!


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Ruggero will be eternally grateful.
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