How to keep iMacs (and Intel Macs in general) cool and quiet

[miretogo]

A few days ago, I received a used 2020 iMac with i7 and 5500XT. During intensive tasks such video encoding (under macOS) or gaming (under Windows), the CPU quickly reached 100 °C despite major fan noise. Since both the temperature and the noise were unacceptable to me, I searched for a solution. Since the solution I found was so easy and effective, I wanted to present it here so that it can maybe help someone else.

macOS:
I installed the free tool Turbo Boost Switcher and disabled the CPU's Turbo Boost. There is a pro version with more features if you want to support the developer.

Windows (10):
I used the Power Options to set the "Maximum processor state" to 99% (instead of the default 100%).

In both cases, the effect is the same: Instead of boosting towards 5 GHz, the CPU now stays at 3.7 Ghz maximum under full load and stays cool (max. 75 °C at full load instead of max. 100 °C) and quiet (the fan stays at the minimum 1,200 RPM instead of almost 3,000 RMP). The performance hit is small and, in my opinion, often not even noticeable.

 

[miretogo]

If you buy the pro version of Turbo Boost Switcher (for $9.95), you don't have to enter your user passwort each time after rebooting. By the way, the CPU temp it shows seems to be "wrong". It seems to show "CPU Proximity" instead of the actual CPU. So don't be surprised if the temp doesn't go up at all when the CPU is working hard. If you want to monitor temps, Macs Fan Control seems to be the better option.

 

[Nicole1980]

You can also turn off hyperthreading - which is borderline useless anyway. Explanation here:

 

[miretogo]

That's interesting, thank you for sharing that! I will think about disabling it and see if how it affects performance on the one hand and temperature/noise on the other. I couldn't find a detailed analysis of that online. However, I don't expect the temperature/noise reduction to be as drastic as the one resulting from disabling Turbo Boost.

 

[miretogo]

While looking at Windows PCs and not Macs, the following detailed article indicates that disabling Hyperthreading reduces system power consumption by up to 10% (no much mut not insignificant, either) and, depending on the application, either increases or decreases performance:

How Screwed is Intel without Hyper-Threading?

Today we're exploring the impact disabling Hyper-Threading has on Intel processors. We've done this in the past and it's an interesting test, however there are new incentives...

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