CPU temperature

Yep.

Absolutely.

If your iMac thinks otherwise it will ramp up the fans or failing that simply shut down to protect itself.

Unless your iMac fans are roaring constantly, it's well within the normal operating range for your CPU.

Doesn't seem particularly problematic - as others said, your CPU fan is running reasonably slow, so the system doesn't think it needs extra cooling.

How hot does it get when doing real work? If you get to 100deg C, that might be worrisome...

That's slightly higher than average, but it's summer there right? I guess it's understandable then. If in doubt, you can always install SMC Fan Control to manually increase your fan speed and cool down your system.

chevalier433 said:

You think average CPU Core temp at idle 60C is normal? View attachment 349279

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Quite normal. The Intel processors used in Macs are designed to automatically shut down to prevent damage if they truly overheat. CPU Tjmax = 105C (221F), GPU Tjmax = 100C (212F) on i3, i5, i7 processors. (Source: Intel) If you're not already using it, iStat Pro will give you accurate readings of your temps and fan speeds, among other things.

Unless there is a rare defect in a Mac, most temps are well within the normal operating range, considering the workload being put on it. Websites with Flash content, games and other multimedia apps will put higher demand on the CPU/GPU, generating more heat. This is normal. If you're constantly putting high demands on your system, such as gaming or other multimedia tasks, expect temps to rise and fans to spin up accordingly. It's just your Mac doing its job to maintain temps within the normal range.

It is also quite normal for your Mac to become extremely hot to the touch during intensive operations. The aluminum body transfers heat more effectively than other materials used in computer casings, so you will feel the heat more. This doesn't indicate that it's overheating and will not harm the computer to be hot to the touch.

Your fans are always on when your Mac is on, spinning at a minimum of 2000 rpm (for MBPs) or 1800 rpm (for MBAs, MBs and minis). iMacs have 3 fans with minimum speeds in the 800-1200 range. They will spin faster as needed to keep temps at a safe level. If they're spinning up without increased heat, try resetting the SMC. (PRAM/NVRAM has nothing to do with these issues, so resetting it will not help.)

The intake and exhaust vents are in the back of the computer near the hinge on all Mac notebooks (except the new MBP with retina display, which has intake vents along the sides at the bottom). The iMac vent is a slot on the back near the top of the computer. Make sure the vents remain unblocked to allow your computer to perform at its best.

Learn about the fans in your Mac
Apple Portables: Operating temperature

For Flash-related issues:

• Find your Flash version and make sure it's the latest version available.
• Install ClickToFlash (Safari), Flashblock (Firefox) or FlashBlock (Chrome) to control which Flash content plays on websites.
• Use the YouTube HTML5 Video Player to watch YouTube videos, when available. (May impact fullscreen viewing. See link for details.)

55*C to 70*C on average is normal.

chevalier433 said:

View attachment 349369

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Change "My Processes" to "All Processes" at the top of the Activity Monitor window. Also click on the System Memory tab at the bottom.

chevalier433 said:

Thank you all for your answers but i think i have problem with my iMac the Core temperature is too high with 10% usage goes to 80 C I occasionally mod my computer maybe something is not connect well i dont know

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That doesn't seem right. I am not at my iMac at the moment(2009 27" i7 2.8GHz) but IIRC my idle temps are down in the 40's C with fans bumped to 1500rpm with iMac Fan Control. Inlet air is about 25C. I prefer running my fans at a slightly higher minimum RPM to improve long term reliability of the CPU/GPU at expense of "maybe" needing to replace a fan at a later date due to 25% extra revolutions. I can't even hear my fans at 1600rpm so noise is not an issue for me in my environment.

I believe at full load I am only getting in the 60's C at which point I have iMac Fan Control spinning the CPU fan up to about 2400rpm.

http://www.derman.com/iMac-Fan-Control

I will see if I can run a few experiments and capture some screen shots for you.

chevalier433 said:

You watch CPU Heatsink or Core temperature?

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Both. Fan Control watches heat sink temp which gives it good stability (not reacting too quickly to core temp). But I also use istat menus and watch my core temps as well.

I guess the "problem" is solved based on how or what YOU define as a problem.

The temps you showed back in July would, most likely, never cause a computer problem for you.

OTOH - that temp bothers you and you have solved that problem.

Approaching 90 degrees C under heavy rendering load is not unusual nor shown to be problematic.

So you are now running cooler - you feel better - that is cool.

chevalier433 said:

You think average CPU Core temp at idle 60C is normal? View attachment 349279

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My older iMac with an i5 idles at aroud 50C. I'd be worried about 60c idle. Are you sure its not doing something in the background?

I thought modern CPUs were supposed to be "efficient"?

My average CPU temp right now at idle is 25c with a 20c ambient temp. The highest its ever been is 70c.