[Server-devel] do RPi 3 B+ still need heat sinks?
Adam Holt
holt at laptop.org
Tue Apr 3 20:35:54 EDT 2018
On Tue, Apr 3, 2018 at 8:17 PM, James Cameron <quozl at laptop.org> wrote:
> On Tue, Apr 03, 2018 at 05:28:31PM -0400, Adam Holt wrote:
> > On Tue, Apr 3, 2018 at 5:01 PM, James Cameron <[1]quozl at laptop.org>
> wrote:
> >
> > On Tue, Apr 03, 2018 at 10:33:12AM -0400, Adam Holt wrote:
> > > On Mon, Apr 2, 2018 at 12:36 PM, Adam Holt <[1][2]holt at laptop.org>
> wrote:
> > >
> > > On Mon, Apr 2, 2018 at 10:44 AM, Adam Holt <[2][3]
> 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 with-heatsink-on-CPU / RPi 3 B+ / RPi 3 B+
> with-heatsink-on-CPU
> > > 44-46C / 46-48C / 45-47C case's plastic top removed (w/o wind or
> active
> > > ventilation)
> > > 46-49C / 48-51C / 48-52C 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 with-heatsink-on-CPU / RPi 3 B+ / RPi 3 B+
> with-heatsink-on-CPU
> > > 80-82C / 70-71C / 71-72C case's plastic top removed (w/o wind or
> active
> > > ventilation)
> > > 82-84C / 75-78C / 79-82C case's plastic top attached (contains
> 100+ small
> > holes
> > > on 1 end, allowing very little ventilation)
> > >
> > > RESULT: attaching a heatsink to the RPi 3 B+ CPU does not help.
> It might
> > even
> > > make things a bit worse, hmm.
> >
> > Yes, your heatsink is no good.
> >
> > The B+ CPU has a heatsink or heat spreader already, that silver
> > coloured bevelled structure with the black dot and Broadcom logo.
> >
> > What is the shape, size, and attachment method for your added
> > heatsink?
> >
> > It's the standard Canakit 7-fin aluminum heatsink shown here, attached
> to the
> > CPU with its own basic 3M self-adhesive sticker:
> >
> > [4]http://www.bestofjay.com/w/
> > raspberry-pi-3-overclock-heat-test-flirc-case-vs-canakit-heatsink/
> > [5]http://11986-presscdn-0-77.pagely.netdna-cdn.com/wp-
> content/uploads/2016/04/
> > heat-sinks-installed.jpg
>
> Given your results, probably wrong heatsink for the job. No, I don't
> know of a better one.
>
Indeed. It'd be really great if the Raspberry Pi Foundation would publish
basic recommendations here, even if just community/testing suggestions.
Theory; the adhesive won't make good contact with outer bevel, and
> passive airflow above that outer bevel will be reduced.
>
> Theory; bubble in adhesive if the heatsink was not angled slightly as
> you pushed it down.
>
> Theory; the thermal control system is very different to the previous
> version, and this invalidates your test method. The system uses
> thermal mass and core frequency scaling, and you've changed the
> thermal mass. It's non-linear.
>
> Report your kernel version; the corresponding Raspbian release has
> changes for the B+.
>
Kernel is 4.14.30-v7+ after 2018-03-28's Raspbian update ("apt update; apt
dist-upgrade; reboot").
See
> https://www.raspberrypi.org/blog/raspberry-pi-3-model-bplus-sale-now-35/
> for more technical detail on the thermals; note how the core frequency
> varies and the thermal mass is a resource.
>
> Suggest you use sysbench for at least 15 minutes before reading the
> temperature. The "yes" test is very weak.
>
Thanks. Any recommended parameters for sysbench to battle-test all RPi 3
B+ subsystems simultaneously?
> FWIW these same heatsinks do lower the temperature of the original RPi 3
> by
> > many degrees IF the CPU 's under medium load AND the top of the plastic
> case is
> > removed :)
>
> But irrelevant, as the CPU is a different model, has a flat surface,
> and does not have a thermal control system that uses thermal mass.
>
> Please remember; things change, and this breaks your knowledge. You
> must learn again.
>
> >
> > > In any case: this result is completely different the original RPi 3
> > (where past
> > > experiments have shown that a heatsink-on-CPU greatly lowers its
> > temperature,
> > > When The Case Is Open!)
> > >
> > >
> > > 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+:
> > >
> > > [3][6]https://cdn-images-1.medium.com/max/1600/1*0jU89Yu_
> > 6miI-CODB
> > > MuHAw.png
> > > [4][7]https://medium.com/@ghalfacree/benchmarking-the-
> > raspberry-pi
> > > -3-b-plus-44122cf3d806
> > >
> > > --
> > > [5]
> > > [6]Unsung Heroes of OLPC, interviewed live @ [7][8]http://
> > unleashkids.org
> > > !
> > >
> > > --
> > > Unsung Heroes of OLPC, interviewed live @ [8][9]http://
> > unleashkids.org !
> > >
> > >
> > > References:
> > >
> > > [1] mailto:[10]holt at laptop.org
> > > [2] mailto:[11]holt at laptop.org
> > > [3] [12]https://cdn-images-1.medium.com/max/1600/1*0jU89Yu_6miI-
> > CODBMuHAw.png
> > > [4] [13]https://medium.com/@ghalfacree/benchmarking-the-
> > raspberry-pi-3-b-plus-44122cf3d806
> > > [5] [14]https://medium.com/@ghalfacree/benchmarking-the-
> > raspberry-pi-3-b-plus-44122cf3d806
> > > [6] [15]https://medium.com/@ghalfacree/benchmarking-the-
> > raspberry-pi-3-b-plus-44122cf3d806
> > > [7] [16]http://unleashkids.org/
> > > [8] [17]http://unleashkids.org/
> >
> > > _______________________________________________
> > > Server-devel mailing list
> > > [18]Server-devel at lists.laptop.org
> > > [19]http://lists.laptop.org/listinfo/server-devel
> >
> > --
> > James Cameron
> > [20]http://quozl.netrek.org/
> > _______________________________________________
> > Server-devel mailing list
> > [21]Server-devel at lists.laptop.org
> > [22]http://lists.laptop.org/listinfo/server-devel
> >
> > --
> > Unsung Heroes of OLPC, interviewed live @ [23]http://unleashkids.org !
> >
> > References:
> >
> > [1] mailto:quozl at laptop.org
> > [2] mailto:holt at laptop.org
> > [3] mailto:holt at laptop.org
> > [4] http://www.bestofjay.com/w/raspberry-pi-3-overclock-heat-
> test-flirc-case-vs-canakit-heatsink/
> > [5] http://11986-presscdn-0-77.pagely.netdna-cdn.com/wp-
> content/uploads/2016/04/heat-sinks-installed.jpg
> > [6] https://cdn-images-1.medium.com/max/1600/1*0jU89Yu_6miI-CODB
> > [7] https://medium.com/@ghalfacree/benchmarking-the-raspberry-pi
> > [8] http://unleashkids.org/
> > [9] http://unleashkids.org/
> > [10] mailto:holt at laptop.org
> > [11] mailto:holt at laptop.org
> > [12] https://cdn-images-1.medium.com/max/1600/1*0jU89Yu_6miI-
> CODBMuHAw.png
> > [13] https://medium.com/@ghalfacree/benchmarking-the-
> raspberry-pi-3-b-plus-44122cf3d806
> > [14] https://medium.com/@ghalfacree/benchmarking-the-
> raspberry-pi-3-b-plus-44122cf3d806
> > [15] https://medium.com/@ghalfacree/benchmarking-the-
> raspberry-pi-3-b-plus-44122cf3d806
> > [16] http://unleashkids.org/
> > [17] http://unleashkids.org/
> > [18] mailto:Server-devel at lists.laptop.org
> > [19] http://lists.laptop.org/listinfo/server-devel
> > [20] http://quozl.netrek.org/
> > [21] mailto:Server-devel at lists.laptop.org
> > [22] http://lists.laptop.org/listinfo/server-devel
> > [23] http://unleashkids.org/
>
> > _______________________________________________
> > Server-devel mailing list
> > Server-devel at lists.laptop.org
> > http://lists.laptop.org/listinfo/server-devel
>
>
> --
> James Cameron
> http://quozl.netrek.org/
> _______________________________________________
> Server-devel mailing list
> Server-devel at lists.laptop.org
> http://lists.laptop.org/listinfo/server-devel
>
> --
> <http://lists.laptop.org/listinfo/server-devel>
> <http://lists.laptop.org/listinfo/server-devel>
> Unsung Heroes of OLPC, interviewed live @
> <http://lists.laptop.org/listinfo/server-devel>http://unleashkids.org !
>
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