CPU/wattage stress test, UPDATED with results

Hello all,

As you can read about here I am trying to push the limits of DC power transmission over Cat 6 cable.

tldr: Power over Ethernet was never designed to do this. It will be risky and still might be impossible.

I need a container that spins up the CPU to the max and any other power-hungry components to max consumption. I was just hoping to find something nearly ready to deploy. If not I will write something and share open source.

I will also post my results here to benefit those who may come later.

Thanks to anyone that wants to comment, even if it is just a note or thought about how to go about this if I have to end up writing it.

I solved this the with simple command:

stress --cpu 4 --timeout 300

5 minutes really gives things time to heat up and will let you know if stuff if going to break. Obvious warning that keeping your CPU pinned tends to reduce performance and may even result in your device showing as offline briefly during the test. I am impressed how stable the shell connection though the dashboard remains most of the time.

Don’t forget to include stress in your apt-get install line of your dockerfile.

Happy testing!


1 Like

My results for the fin:

All test results are powered over POE, see my post here for details. I have 300 ft or 91.44 meters of cat6 cable between the device and the supply switch. Measurements at made by an inline POE power draw meter. Room is temp controlled to around 70 degrees. (This matters a lot) The CPU temp is always 84.9 for the stress tests. (That’s the temp it thermal throttles at.)

The fin is powered directly by the 24.23v power by connecting the POE header pins to the phoenix jack directly. Which after line drop is 23v at the device. The fin then steps this down to whatever it needs.

Test idling:
With my container running nothing but:
-maintianing a wifi connection
-nothing else plugged in
-status LEDs and HDMI turned off
-RGB led set to a power of 20 on one color only

I draw about 4 watts of power at the switch. CPU temp around 54 C

Test cpu LOAD:
-same as above but below running
stress --cpu 4 --timeout 300

Around 6 watts with .15 watts variance, temp max (84.9 C)

Test adapters:
-3 wifi adapters plugged in via USB
Around 7.2 watts

Test adapters plus cpu stress:
Around 10 watts plus or minus 1 watt, starts higher at 11, then drops to 9.5 when it starts thermal throttling.

My results are not scientific! Your mileage may vary! I promise nothing!

This is probably why the spec sheet says 12.5-watt power supply is recommended. :wink:


Hi Thomas,
thanks for posting this on the balena forums, I will ping our engineers involved with the fin about your findings.
Regards Thomas