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iMac CPU running at maximum frequency all the time

Khaleal

macrumors regular
Original poster
Aug 24, 2013
185
75
Specs: iMac (27" Late 2013, i5-4570 3.2GHz, 32GB RAM, GT 755M 1GB), HS 10.13.6

According to Intel Power Gadget, the above iMac is running at 3.2GHz constantly even while idling (with CPU utilisation of less than 1%), when it turbo-boosts it can reach 3.6GHz (but this is normal behaviour when under load).

Is this normal? things that I tried so far: SMC/NVRAM reset, Apple Diagnostics (no errors found).
And the CPU temperature is well under control and it rarely reaches 75 max.
 

chabig

macrumors 604
Sep 6, 2002
7,278
4,531
I don't think so. That's why it's called the base frequency. Parts of the CPU might shut down to conserve energy but the frequency doesn't slow down as far as I know.
 
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Khaleal

macrumors regular
Original poster
Aug 24, 2013
185
75
I don't think so. That's why it's called the base frequency. Parts of the CPU might shut down to conserve energy but the frequency doesn't slow down as far as I know.
Well, I took a course in high performance computer architecture and I now for a fact that Intel CPUs decrease their frequency when they're not under load to save power (this is called power states). and I've observed this happening on my PC and Macbook Pro.

If you have an iMac, do you mind running Intel Power Gadget and checking the frequency your CPU is running at while idling?
 
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CheesePuff

macrumors 65816
Sep 3, 2008
1,081
805
Southwest Florida, USA
Well, I took a course in high performance computer architecture and I now for a fact that Intel CPUs decrease their frequency when they're not under load to save power (this is called power states). and I've observed this happening on my PC and Macbook Pro.

If you have an iMac, do you mind running Intel Power Gadget and checking the frequency your CPU is running at while idling?

Incorrect, only if its being thermally throttled. It's call a base clock speed for a reason.

Processor Base Frequency describes the rate at which the processor's transistors open and close. The processor base frequency is the operating point where TDP is defined. Frequency is measured in gigahertz (GHz), or billion cycles per second.
 
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Khaleal

macrumors regular
Original poster
Aug 24, 2013
185
75
Incorrect, only if its being thermally throttled. It's call a base clock speed for a reason.

Processor Base Frequency describes the rate at which the processor's transistors open and close. The processor base frequency is the operating point where TDP is defined. Frequency is measured in gigahertz (GHz), or billion cycles per second.

Please check this wikipedia article (under Performance States): https://en.wikipedia.org/wiki/Advanced_Configuration_and_Power_Interface#OSPM_responsibilities

It's called SpeedStep in Intel processors
 
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chabig

macrumors 604
Sep 6, 2002
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In the Wikipedia article on SpeedStep, macOS is not listed as an OS that supports it.
 
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FredT2

macrumors 6502a
Mar 18, 2009
566
99
Well, I took a course in high performance computer architecture and I now for a fact that Intel CPUs decrease their frequency when they're not under load to save power (this is called power states). and I've observed this happening on my PC and Macbook Pro.

If you have an iMac, do you mind running Intel Power Gadget and checking the frequency your CPU is running at while idling?
iMac Pro: base frequency is 3.0, seems to hover around 2.0 when not doing anything (Safari and PowerGadget running).
 
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chabig

macrumors 604
Sep 6, 2002
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In System/Library/Extensions there is AppleIntelSlowAdaptiveClocking.kext. That might be a clue, but there is no reason to think that your iMac isn't behaving as designed.
 
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Khaleal

macrumors regular
Original poster
Aug 24, 2013
185
75
There is a kext called "IntelEnhancedSpeedStep.kext" under Extensions. a quick google search will show you many threads of people asking how to disable it (since it's enabled by default).
Also you can see from @FredT2 comment, his iMac is decreasing its frequency while idling.
[doublepost=1563220717][/doublepost]
iMac Pro: base frequency is 3.0, seems to hover around 2.0 when not doing anything (Safari and PowerGadget running).
Thanks for your feedback!
 
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chabig

macrumors 604
Sep 6, 2002
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There is a kext called "IntelEnhancedSpeedStep.kext" under Extensions.
I am running the latest version of Mojave and I do not have this extension. Could it be something that migrated to your system from an earlier installation?
 
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Khaleal

macrumors regular
Original poster
Aug 24, 2013
185
75
I am running the latest version of Mojave and I do not have this extension. Could it be something that migrated to your system from an earlier installation?
I really can't understand why you don't want to believe it's supported in macOS. SpeedStep has been implemented in Intel CPUs for years, and it's supported by every major OS. FredT2 post is a live example of the feature working under macOS.
SpeedStep is implemented and supported in macOS whether you want to believe it or not, and I don't see how this is contributing to the discussion.
 
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priitv8

macrumors 68040
Jan 13, 2011
3,685
505
Estonia
Mine is also defintely clocking down, even under light load.
Screenshot 2019-07-15 at 23.11.27.png
 
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