The Mac Studio may not be a noisy Mac, but its always-spinning fans have one undeniable advantage: you can tell at a glance if the computer has gone to sleep or if it’s still active. . And precisely, it’s been a few days that mine was never silent, its two fans were running constantly, even in standby. First I blamed the external SSD plugged into the back of the computer, but removing it didn’t change anything and this Mac Studio still refused to go to sleep.
After checking several common culprits in such a situation, such as network waking the Mac (in the “Power Saver” panel of System Preferences), then content caching (in “Sharing”), I don’t found nothing. It must be said that the person responsible was more unlikely: it was the Studio Display which kept the Mac awake and more specifically its “Hey Siri” function.
To find out, I used the command line
pmset -g assertions in the terminal of macOS. This tool can be used to understand why a Mac refuses to go to sleep, by listing the causes of insomnia. In my case, I had an assertion of type
PreventSystemSleep which allowed me to find the process responsible for the blocking:
PreventSystemSleep named: "com.apple.corespeech.powerassertion"
” corespeech is the name of the framework associated with Siri, Apple’s voice assistant. I then made the connection: I received the Studio Display at the end of the week and the standby problems actually started at the same time. A quick test confirmed the problem: by unplugging the screen, the Mac Studio instantly goes to sleep and turns off its two fans.
Since Siri is involved, it’s not so much the screen itself that’s the problem, but rather the “Hey Siri” function. As a reminder, the Studio Display is able to activate the voice assistant without touching the keyboard or the macOS interface, but only by voice as on iPhones, iPads and Apple watches. It is this function that blocks my Mac from sleeping, but it is not necessary to completely disable it.
According to my tests, uncheck the option ” Allow Siri when device is locked in the Siri panel of System Preferences is enough to fix the problem. The voice assistant then remains available when the Mac is active, but is deactivated when it goes to sleep. Since I unchecked this box, the Mac Studio normally goes to sleep, even with all accessories plugged in.