Zero 3W running hot

I have noticed a tendency for the Radxa Zero 3W to run hot even under moderate load. This seems to be true for the CPU itself, but also the black chip next to it (RAM?).

I am running the Zero 3W with the Debian Bullseye image. According to cpufreq-info, the kernel already uses the “ondemand” governor.

$ cpufreq-info
cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Bitte melden Sie Fehler an cpufreq@vger.kernel.org.
analysiere CPU 0:
  Treiber: cpufreq-dt
  Folgende CPUs laufen mit der gleichen Hardware-Taktfrequenz: 0 1 2 3
  Die Taktfrequenz folgender CPUs werden per Software koordiniert: 0 1 2 3
  Maximale Dauer eines Taktfrequenzwechsels: 149 us.
  Hardwarebedingte Grenzen der Taktfrequenz: 408 MHz - 1.42 GHz
  mögliche Taktfrequenzen: 408 MHz, 600 MHz, 816 MHz, 1.10 GHz, 1.42 GHz
  mögliche Regler: ondemand, performance, schedutil
  momentane Taktik: die Frequenz soll innerhalb 408 MHz und 1.42 GHz.
                    liegen. Der Regler "ondemand" kann frei entscheiden,
                    welche Taktfrequenz innerhalb dieser Grenze verwendet wird.
  momentane Taktfrequenz ist 1.42 GHz.
  Statistik:408 MHz:6.38%, 600 MHz:10.76%, 816 MHz:0.00%, 1.10 GHz:0.24%, 1.42 GHz:82.62%  (42667)
analysiere CPU 1:

So, I guess this is by design and the only thing I can do is use a better heat sink? Or is there anything else I could do?

At the moment, I am using the standard heat sink sold by Alltech.

For my application, I need the hole setup to be flat and I cannot have active cooling.
Doing some research I came across this solution for the Raspberry Pi Zero, which may also work for the Zero 3W.

Anyone able to share some experience in this regard?

The board rendering video from the camera can reach 85ºC on my experiments.
I finally got a working u-boot with my kernel (and wifi) and soon can test some optimizations with ubuntu and see what i get.

I think HDMI output is to blame… Have you tried disabling HDMI?

No I have not. That would be somewhat counter-productive since I am using the Zero 3W for a digital photo frame application. I am afraid HDMI output is required. However, I could live with low performance settings since the photos are fairly static.

When I said hot before, I meant I burn my fingers if I touch the heat sink for more than 2 seconds. In the meantime, I have found sensor readings in the sys file system. This is what I get after indexing a few thousand photos:

Zone 0: 72.8 °C
Zone 1: 71.1 °C

Not extreme, but from my experience rather high. I am more used to temperatures around 60 °C with other SBCs.

root@radxa-zero3:/home/rock# cat /sys/devices/virtual/thermal/thermal_zone0/hwmon0/name
soc_thermal
root@radxa-zero3:/home/rock# cat /sys/devices/virtual/thermal/thermal_zone1/hwmon1/name
gpu_thermal

Have you tested that heatsink ?

I ordered one of this to see it it fits: