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I am running Raspian 9.4 Stretch and access it through SSH. How can I determine whether my RaspberryPi (3B+) is currently in a state of thermal throttle? I know I can get the RasPi's temperature using vcgencmd measure_temp, but what is the actual temperature target, when the Pi starts throttling? Is this target temperature something that is determined by the OS I am currently using? Or is it defined inside the SoC's firmware? How could I read it from the firmware? Can I change it? Is there a way to get the thermal throttle indicator from Raspian GUI inside SSH terminal?

Unfortunately the vcgencmd get_throttled command seems not to include all throttle states. e.g. I get this when NOT using a fan for cooling: $ vcgencmd measure_clock arm && vcgencmd measure_temp && vcgencmd get_throttled frequency(45)=1200000000 temp=70.4'C throttled=0x0

and this when using a fan: $ vcgencmd measure_clock arm && vcgencmd measure_temp && vcgencmd get_throttled frequency(45)=1400000000 temp=62.3'C throttled=0x0

CPU throttles down from 1.4 GHz to 1.2 GHz, but vcgencmd get_throttled still shows 0x0.

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Try vcgencmd get_throttled

See https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=147781&start=50#p972790 which shows

    0: under-voltage
    1: arm frequency capped
    2: currently throttled
    16: under-voltage has occurred
    17: arm frequency capped has occurred
    18: throttling has occurred
  • The CPU does not throttle down until it hits 80 C. I think you are confusing the effect of the "on demand" governor for throttling. – goldilocks Apr 23 '18 at 12:16
  • I am currently using BOINC to get a load on my RasPi CPU. What I am observing is, that below 70°C the CPU works with 1.4 GHz. But as soon as the temperature exceeds 70°C the CPU "throttles" to 1.2 GHz. I do not know how else I could describe this behaviour if not with "throttling" – jschfr Apr 23 '18 at 12:44
  • @jschfr DO NOT paste detail in Comments - Edit into your question. – Milliways Apr 23 '18 at 23:42
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what is the actual temperature target, when the Pi starts throttling?

According to this post from an Rpi engineer (which is quite old, but appears to have been updated in 2016), the CPU is throttled at 80 C and the GPU at 85 C. This makes sense as it is unlikely they would do it unreasonably within the confines of the operating parameters (safe up to 85 C) but would not want to allow it to go far beyond that point either. I.e., it is not intended to take effect when the system is just getting warm, it is intended to take effect when it is getting too hot.

Is this target temperature something that is determined by the OS I am currently using?

That post explicitly refers to firmware, so no, it is not the OS. You may still be able to configure it using the setting mentioned there (this would be in config.txt). Although it is not clear that you could raise it beyond 85 C, you can at least test it by lowering it via temp_limit.

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