[SOLVED] RPI4 Aarch64: SoC gets 9 C hotter

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[SOLVED] RPI4 Aarch64: SoC gets 9 C hotter

Postby doragasu1 » Fri Mar 19, 2021 3:34 pm

I have a RPI4 running as home server. The install is 32-bit, and I wanted to update it to a 64-bit aarch64 system.

So I grabbed another RPI4 and sd card and started a new install. But I found a bit surprised that the base system with almost anything installed gets a lot hotter with this setup. My current 32-bit install stays about 50 C with light load, while this new aarch64 install stays at 59 C while idle.

Is this expected? Is there a way to improve the power usage of the aarch64 image or should I stay on armv7 release if I want to keep temperature lower?

Also which features will I miss when switching from armv7 to aarch64? The installation guide is not clear about this.
Last edited by doragasu1 on Sun Apr 11, 2021 8:56 am, edited 2 times in total.
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Re: RPI4 Aarch64: SoC gets too hot

Postby graysky » Fri Mar 19, 2021 3:50 pm

Firstly, 60C is not too hot. Too hot is when throttling occurs so your title is a bit misleading.

I haven't noticed difference arm7h vs aarch64. What is the system load when "idle" as read by uptime under each system and how are you measuring the temp?

Here is a little script I use for stuff you might like:
$this->bbcode_second_pass_code('', '#!/bin/sh
temp=$(cat /sys/devices/virtual/thermal/thermal_zone0/temp)
freq=$(sleep 0.1s && cat /sys/devices/system/cpu/cpufreq/policy0/scaling_cur_freq)
gov=$(cat /sys/devices/system/cpu/cpufreq/policy0/scaling_governor)
vcore=$(vcgencmd measure_volts core | awk -F"=" '{ print $2 }')

echo "CPU temp : $(( temp / 1000 ))°C"
echo "CPU freq : $(bc <<< "scale=0; $freq/1000") MHz @ $vcore ($gov)"
echo "Thermal brake : $(vcgencmd get_throttled)"
echo "Processor : $(grep -m1 'model name' /proc/cpuinfo | sed 's/^.*: //')"
')
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Re: RPI4 Aarch64: SoC gets 9 C hotter than when using armv7

Postby doragasu1 » Fri Mar 19, 2021 6:12 pm

You are right, title is not precise, I have edited it.

I am measuring like you do in your script, from /sys/devices/virtual/thermal/thermal_zone0/temp

Load for the armv7 at 50/51 C: load average: 0.59, 0.65, 0.61
For the aarch64 after 20 minutes uptime:
$this->bbcode_second_pass_code('', '[jalon@alarm ~]$ cat /sys/devices/virtual/thermal/thermal_zone0/temp
55504
[jalon@alarm ~]$ uptime
18:10:16 up 20 min, 1 user, load average: 0.00, 0.00, 0.00')

It did not reach 59 C, but it is at 55.5 C while sitting idle. The other armv7 board has light load and is cooler.
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Re: RPI4 Aarch64: SoC gets 9 C hotter than when using armv7

Postby graysky » Fri Mar 19, 2021 6:25 pm

50/51 vs 56 is similar but well within safe range. Is this the identical board (ie you just swapped uSD cards and booted) or two different RPi4Bs? Are they in the same room?
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Re: RPI4 Aarch64: SoC gets 9 C hotter than when using armv7

Postby doragasu1 » Sat Mar 20, 2021 3:49 pm

They are in the same room. The board is not exactly the same, I am using a different board to keep my server running while I do experiments.

* armv7 board is a RPi4 with 4 GiB RAM
* aarch64 board is a RPi4 with 2 GiB RAM

Unless there is another difference I am not noticing, the 4 GiB board should be at disadvantage (because more RAM should drain more energy and generate slightly more heat), but is in fact cooler.

Anyway, I suppose difference is not that big. If I am the only one noticing this, maybe it is just a problem with the board. :?:
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Re: RPI4 Aarch64: SoC gets 9 C hotter than when using armv7

Postby graysky » Sat Mar 20, 2021 4:24 pm

If you're comparing armv7h to aarch64 on two different boards you're not conducting a fair comparison. You have to test with one variable. Use the same board and swap the uSD card. That is assuming the same packages/services/etc. are set-up on each uSD card (armv7h vs aarch64).
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Re: RPI4 Aarch64: SoC gets 9 C hotter than when using armv7

Postby doragasu1 » Sat Mar 20, 2021 5:44 pm

OK, I will do a better test when I finish moving everything I have in the armv7 board to the SD I am preparing with the aarch64 install.

I just wanted to avoid spending hours migrating everything to the aarch64 architecture if that will result in a sensible increase in the power drain and heat (and will make me go back to the old setup). Because even though it is true the comparison is poor because there are several variables at play, unless I am missing something, if we set aside the architecture, all the other variables are less favorable to the armv7 board (complete system running a lot of services vs base install running nothing and 4 GB vs 2 GB).
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Re: RPI4 Aarch64: SoC gets 9 C hotter than when using armv7

Postby graysky » Mon Mar 22, 2021 8:12 am

Also worth noting that power consumption and heat produced are two different variables. Power consumption can be measured with external hardware (Kill-A-Watt which you can buy off amazon, maybe other brands too).

On my RPi4B with 8G of RAM which is both overclocked (2000 MHz) and actively cooled via a small fan powered by the 3.3V pin), the Kill-A-Watt (no decimal places so I assume it rounds to the nearest W):

Under armv7h:
Idle = 2 W (either ondemand or performance governor).
Load = 7 W (running cpuburn which is maxing out all 4 cores).

Under aarch64:
Idle = 2 W (either ondemand or performance governor).
Load = 6 W (running cpuburn which is maxing out all 4 cores).
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Re: RPI4 Aarch64: SoC gets 9 C hotter than when using armv7

Postby unformatted » Sun Mar 28, 2021 1:12 pm

I wouldn't use a fan on 3V3. That's an internal voltage regulator which already gets hot and adding anything to it will only increase temperature.

I use the following housing for years (first on RPi3 and now on RPi4): http://www.akasa.com.tw/update.php?tpl=product/product.list.tpl&type=Fanless%20Chassis&type_sub=Fanless%20Raspberry%20Pi. I just maxed out all 4 cores 100% for 10 minutes and temperature never exceeds 42 degrees Celcius using /opt/vc/bin/vcgencmd measure_temp.

Although the Pi can tolerate high temperatures, electronic components do degrade faster on higher temperatures so a little investment on a decent aluminium housing with a thermal kit is money well spent.
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Re: RPI4 Aarch64: SoC gets 9 C hotter than when using armv7

Postby doragasu1 » Sat Apr 10, 2021 7:33 pm

Finally I got the time to move everything to the aarch64 install, and I you are right, now I cannot notice a difference. It seems my initial suspicion was wrong.

Now I have other problem (with Kodi, but I opened other thread for that).
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