[Server-devel] do RPi 3 B+ still need heat sinks?

[Adam Holt]

On Mon, Apr 2, 2018 at 10:44 AM, Adam Holt <holt at laptop.org> wrote:

> 1) Recap from 2016: heatsinks on the original RPi3 CPU are not a cure-all
> when the RPi 3 is enclosed in a case that lacks ventilation on a hot day.
> But CPU heatsinks Do Work when taking the plastic top off the of the
> original RPi 3.  The CPU throttling problem "immediately" goes away on such
> hot days...bringing the temperature back down below 80C...as measured by
> the command:
>
>    *vcgencmd measure_temp*
>
> 2) It's snowing today right outside my window, so I can't easily simulate
> a hot summer's day -- but can others who live in hot environments report
> back their readings above, when running the new RPi3 B+ in various
> conditions?
>
>    - *With heatsink on CPU -- and without?*
>    - *With motherboard fully enclose by a case -- and without?*
>
>
My own results, with all 4 CPU's unloaded, in a chilly room:

  RPi 3 / RPi 3 B+
44-46C / 46-48C case's plastic top removed (w/o wind or active ventilation)
46-49C / 48-51C case's plastic top attached (contains 100+ small holes on 1
end, allowing very little ventilation)

After I ran "*yes > /dev/null &*" 4 times, to fully load all 4 cores of the
CPU:

  RPi 3 / RPi 3 B+
80-82C / 70-71C case's plastic top removed (w/o wind or active ventilation)
82-84C / 75-78C case's plastic top attached (contains 100+ small holes on 1
end, allowing very little ventilation)


CONCLUSION: the RPi 3 B+ appears to be a real winner in CPU-intensive
conditions, even in a "wintry" conditions (room is about 15C, and it
continues to snow right outside the window).  The RPi 3 CPU is supposed to
self-throttle at 80C, until it just about turns itself off at 85C.  I'd
assume the RPi 3 B+ CPU does the same?  But do not know for sure.  Thanks
to all who can add any similar data points, in warmer climate/conditions.


CLARIFS:  Both RPi's were running a near-final prerelease of
Internet-in-a-Box 6.5 on Raspbian Lite to explore real-world conditions.
I waited 10+ min in all above 8 experiments before taking "steady state"
temp readings.  Still, fluctuations in CPU activity (and temperature)
arise, even long after I ran "killall yes" to end the most intensive CPU
activity.


3) Prelim thermal analysis of RPi 3 B+:
>
> https://cdn-images-1.medium.com/max/1600/1*0jU89Yu_6miI-CODBMuHAw.png
> https://medium.com/@ghalfacree/benchmarking-the-raspberry-
> pi-3-b-plus-44122cf3d806
>
> --
>
> <https://medium.com/@ghalfacree/benchmarking-the-raspberry-pi-3-b-plus-44122cf3d806>
>
> <https://medium.com/@ghalfacree/benchmarking-the-raspberry-pi-3-b-plus-44122cf3d806>
> Unsung Heroes of OLPC, interviewed live @
> <https://medium.com/@ghalfacree/benchmarking-the-raspberry-pi-3-b-plus-44122cf3d806>
> http://unleashkids.org !
>
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