Acceptable CPU Temperature On Macs


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Questions and Answers : Macintosh : Acceptable CPU Temperature On Macs

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ChrisBWatching
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Message 935166 - Posted: 22 Sep 2009, 1:57:22 UTC

Hello:
My inquiry is about the following Mac Models:

Model Name: Power Mac G5 Quad
Model Identifier: PowerMac11,2
Processor Name: PowerPC G5 (1.1)
Processor Speed: 2.5 GHz
Number Of CPUs: 4
L2 Cache (per CPU): 1 MB
Memory: 8.5 GB
Bus Speed: 1.25 GHz
Boot ROM Version: 5.2.7f1
OSX 10.5.8

And

Model Name: iMac
Model Identifier: iMac7,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.4 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 4 MB
Memory: 1 GB
Bus Speed: 800 MHz
Boot ROM Version: IM71.007A.B03
SMC Version (system): 1.20f4
OSX 10.6.1

CPU Usage is set to 60%
Temp on both computers runs from 50°C to 60°C

Recently I have been attempting to find an article with definitive acceptable cpu temps for these two machines. I have found several that discuss leaking liquid cooling pumps burned out mother boards, etc. I have also found articles suggesting that CPU temps are ok up to 100° C. It will be appreciated if someone out there can help me understand whether or not I am gradually melting the guts of these machines.
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Message 935196 - Posted: 22 Sep 2009, 4:42:15 UTC - in response to Message 935166.

I have my iMac at 100% 24/7 and my temps are mainly around 50˚C.

I do use smcFanControl to boost my fan speeds though. Works on Intel machines only though.
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Message 935254 - Posted: 22 Sep 2009, 15:02:32 UTC
Last modified: 22 Sep 2009, 15:07:08 UTC

From what I have seen, 100c is to hot for a G5 processor. I run a Power Mac G5 and the hottest processor gets to around 72c or 162f. As I recall the rating on the chip was 170f. My processors is running 100% and the fans speed changes to hold these numbers. If I shut down Boinc the fan speed will drop and the chips will run cooler. I do open my system up once a year in the early summer and blow the dust out. This can slow the fans down by up to 200 rpm. As for leaks, I do have a water cooled system and I have seen no sign of leaks.
I have had the system for over 3 years and had no problems with it. On the other hand I did blow an add on memory in my G4 Ibook and it's not running Boinc, but that's another story.
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Message 935286 - Posted: 22 Sep 2009, 22:11:08 UTC

Oh I think I hate Intel. I have been working with motorola 68k where heat is not an issue and you have to pull teeth to get that data from Intel. In any case, from this Link I think the number you are looking for is 72.4C. If this is the chip you are running, then 100C is getting carried away. You may be looking at custom over clocked systems which is not what Apple produces. Most chip companies tend to pick the same temperatures for chips in the same family and most of the time, 100C is reserved for military grade semiconductors. You may want to poke around a little more on the link if you want to double check me.
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Message 935296 - Posted: 22 Sep 2009, 23:18:32 UTC
Last modified: 22 Sep 2009, 23:19:15 UTC

I have to stop doing this. I found this statement “Note: Maximum power at 85°C is the only value that is guaranteed by manufacturing test. Values for typical at 65°C, maximum at 105°C, nap, and doze are not guaranteed by test. These values are to be used as characterization-based nominal values and are included for comparison purposes only. “ in this document Power PC Manual . While the chip is able to run up to 105C, it is not recomended and it appears that Apple has set the fans up to stay in the safe zone.
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Message 937807 - Posted: 5 Oct 2009, 21:28:48 UTC

My dual-core G5 has been at 72–74°C almost continuously for the past three years—“almost” only because of a couple of power failures, and rebooting after OS upgrades—with no problems or signs of strain on the cooling system.

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Message 938401 - Posted: 8 Oct 2009, 19:01:36 UTC - in response to Message 935166.

ark.intel.com has all the processor families that you can drill down into to find and compare features on (that Intel cares to list).

Tho Apple seems to get custom runs from Intel - it could still provide some useful info on the processor families (7000, 8000, EE's, etc)

in the core2duo mobility section the processors with Max TDP's posted were pretty much all in the 100c or better range.

But even if the CPU can survive 100c and above tho, given the tight quarters of the iMac and MacBooks - how to put it subtly - I'd not like the CPU to be the sole survivor.

Are there any adjustable (terminal? plist, hidden?) parameters for minimum fan speeds, or is that better left to third party stuff like SMC?

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Message 938470 - Posted: 8 Oct 2009, 23:10:58 UTC

In the current crop of Apple systems, the fan seems to be controlled by the temperature of the processor and other parts of the system. The warmer things get, the faster the fans run to control the temperature. The big warning is that Apple rates most of their systems for 95 degrees F so if you are going to run your system in a very warm room, you should watch things close. I suspect you can go over 95 degrees as long as your system is idle most of the time and not generating much heat. I have done that with my Ibook and the fan never came on. The programs you are talking about will run the fan faster than Apple calls for and are best for a laptop to keep from burning your lap. The down side of those programs is they will shorten the life of your fans. In server grade hardware, the fans are intended for heavy use, but in Laptops, I am not sure the fans will take years of running.
The best advice I can give you is to get Istat pro and watch your system for a few days before deciding what you want to do. If you have server grade hardware, you shouldn't have to worry, but other lighter duty hardware may require you to run the fans faster or to allow boinc to have only part of the processor power.
I don't run Boinc on my Ibook because I don't feel it was intended for that type of abuse. On the other hand, my power mac G5 is on between 16 and 24 hours a day for other reasons and was designed for 100% processor usage.
I am repeating myself, but make sure you blow the dirt out of a system that's running hard. That alone will allow the fans to move more air at a slower speed.
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Questions and Answers : Macintosh : Acceptable CPU Temperature On Macs

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