Model A1224 / Mid 2007 and Early 2008 / 2, 2.4, or 2.66 GHz Core 2 Duo processor

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CPU usage at 100% causing overheating

My father just gave up on this iMac since it have this overheating/full processing for long time.

He tried to some specialized apple partner here in Brazil, cleaned up fans, etc, updated to Snow Leopard, upgraded RAM to 8Gb... but no solution...

So I got the iMac with 8Gb RAM, 500GB HD with 50% usage and I'm trying to identify the issue.

So, I've got some scenarios...

1st scenario:

- dashboard with some widgets (istat pro, weather, calc);

- running safari, chrome;

Result: after about half an hour, it keeps growing CPU usage to about 70% and then suddenly goes up to 100%.

2nd scenario:

- dashboard with no widgets;

- running chrome;

Result: running fine, half an hour later, started to configure mail, notification center and opened App Store, CPU usage runs up to 100%.

3rd scenario:

- running chrome;

- downloading Mavericks;

Result: running normal. Low CPU usage (around 10%, 15%) with some peaks around 60%.

4th scenario:

- only downloading Mavericks;

Result: running normal. CPU usage at 5% with some peaks around 20%.

Tried some tips that I found at Apple Support forums (SMC and PRAM Reset).

Any tips?

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1 Answer

Chosen Solution

Your scenarios don't really matter here. You need to ID the guilty app or process using 'Activity Monitor Locate the app in your Apps folder and leave it running watch what holds the CPU cycles even when you are not doing anything. I would also recommend installing a thermal & fan monitoring app like Temperature Gauge, others will also work. Monitor the sensors and fans to see if there is something amiss.

Also did you replace your HD? Or do you still have the original HD. Why this matters is often people forget to alter theHD's SATA I/O speed to match the systems limits. Running a SATA III (6.0 Gb/s) in these older systems can create issues which appear as a software issue but is a hardware issue with the HD (incorrect drive or not correctly setup). Check your HD specs and compare them to your systems HD channel limits. Do they match?

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I would hold off upgrading to Mavericks for now.


it's the original HD. How do I check system HD channel limits?

Installed Temperature gauge pro.

now, running safari, chrome, garage band, imovie, iphoto, temperature gauge pro, calendar, mail... the processor usage seems to be ok.

it goes up to almost 100%, the temperature goes up, everything gets a little bit slow, the fans begin to run at full speed, then, the processor goes down and everything is back to normal....

this mainly is happening when I do something at iTunes and a process called coreaudiod is shown in the top 5 of the CPU usage list.

but after the fans are at full speed even the process usage goes down a little bit.

do you think it might be an issue on CPU cooling system?


Even a bad cooling system will not increase your processor usage. It is the other way around; the greater the demand on the processor the hotter it gets. Follow the advice given by Dan and check your background processes.


Your systems HD SATA port is SATA II (3.0 Gb/s).


How much RAM does your system have in it? You appear to be running a lot of stuff concurrently. This series had 1 or 2 GB or Ram did you upgrade it and if so how much? Also how full is your HD and what is it size.


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