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I have a 2.8 GHz Intel Core i5 27" iMac. It is two years old. It feels very hot. I have downloaded iStat nano and the temperatures (degrees Celsius) are:

HD: Macintosh HD 54 °C
CPU A 55 °C
GPU Diode 63 °C
GPU Heatsink 57 °C
Ambient 23 °C
Memory Controller 53 °C
Optical Drive 52 °C

Is this normal? I am a little concerned. Please advise.

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closed as too localized by Breakthrough, 8088, soandos, Ƭᴇcʜιᴇ007, Nifle Sep 3 '12 at 20:39

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

Did you measure those temperatures when the computer was idle or under load? If the latter, what kind of load? – Indrek Sep 3 '12 at 12:23
@aliasgar - FYI, any edits on questions that are closed or on hold are supposed to first solve the hold/close issue. Editing a closed/on-hold question throws it into the reopen queue and wastes people's time if the original issue is still there. – fixer1234 Feb 18 '15 at 16:08
@fixer1234 removed the tag – aliasgar Feb 19 '15 at 6:57

If a CPU temperature of 55 ºC and a GPU temperature of 63 °C is normal or not depends on the exact model (fan control) and if the processors are under load or not.

What's worrisome is the fact that the hard disk and optical drive almost match the temperature of your CPU. Again, this depends on the exact model, but more often than not, it means that the exhaust vents of the laptop are clogged up with accumulated dust. As a result, the CPU can't be properly cooled, and the heat it generates spreads through the entire laptop.

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Those are all normal. Since your iMac has thermal throttling, the temperatures don't tell you much. Your cooling could be excellent and your computer running at full speed or your cooling could be terrible and your components are throttling to stay at those temperatures.

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I disagree. 54 °C is a bit high for the hard drive, and 63 °C is also high for the GPU (assuming those are idle temps). – Indrek Sep 3 '12 at 12:25
@Indrek: Idle temps just measure how much the fans can slow down. They don't measure anything particularly useful. – David Schwartz Sep 3 '12 at 12:26
That may be, but my point was that, until the OP has specified whether he got those temps while idle or under load, there's little point in trying to assess whether they're normal or not. If he's getting those temps while idle, then most of them are definitely not normal, even for a Mac. – Indrek Sep 3 '12 at 12:30
They're normal either idle or under load. Under idle, you're just measuring how much the fans can slow down. The typical spec for thermal management on a laptop HD is 55C, so 54C is consistent with properly-functioning thermal management. – David Schwartz Sep 3 '12 at 12:46
  • Your Hard Drive temperature looks a bit high.

  • Your Optical Drive temperature also seems high.

  • Rest looks good.

  • Attaching a screenshot of the iMac at my office. And these are the temperatures of a machine which is NOT idle.

iMac Temperatures

  • If your iMac is idle, then all of those temperatures are high.
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