fourdee4d
Posts: 362
Joined: Mon Sep 17, 2012 10:31 pm
Location: East Midlands, UK
Contact: Website

RPi 3 Heatsink + Case combo (55'c MAX)

Thu Oct 20, 2016 4:24 pm

Intro:

Cogent.design: https://cogent.design/

The Cogent.design Raspberry Pi 3 case is a heatsink + metal case, built into one complete and gorgeous unit:
Image
The heatsink design is built into the top section of the case:
This basically turns the whole case, into one giant heat dissipating goddess of a heatsink.
Image


How does it perform as case?

Positives:
  • Its a heatsink and case, all built into one.
  • Although the CPU will transfer all heat to the case, other components will heat up. This has been thought out well in the case design and features various slots and holes for air ventilation
  • The metal finish on the exterior of the case is exceptional, with a glistening brushed finish and no sharp edges, high quality craftsmanship throughout and it shows.
  • The thickness of the metal is roughly 3mm thick, its extremely high quality and exceptionally strong.
  • There is also a satisfying weight to the case, it feels like its built to last.
  • The case is provided with 4 adhesive, soft gel feet pads to prevent slip.
  • There is only 2 parts to the case, a top and bottom.
  • Both the top and bottom parts of the case, appear to be created from a single mold with no additional welding.
  • Also doubles up as a hand warmer.
Negatives:
  • There is no access to GPIO built into the case design. The top section would need to be removed for access.
How does it perform as a heatsink?
When we consider the heat will be dissipated through the whole case, with a large surface area, one should expect great results.

Lets run some CPU stress tests:
I ran two Raspberry Pi 3's at the same time, one with the Cogent.design case, and the other with a standard case.
Image
The stress tests consisted of a 8 thread CPU burn. The reason for using 8 threads is to ensure CPU overheads occur, maximizing the stress on the CPU and heat generated.

The test is run for 10 minutes using the following commands:

Code: Select all

apt-get install -y stress 
stress -c $(( $(nproc --all) * 2 )) -t 600 &
while (( $(ps aux | grep -ci -m1 '[s]tress') )); do echo -e "$(date) | $(( $(cat /sys/class/thermal/thermal_zone0/temp) / 1000 ))'c"; sleep 1; done
Stress test results:
  • Idle temps:
    • Cogent.design Case = 35'c
    • Stock case = 48'c
  • Max temps reached from stress test:
    • Cogent.design Case = 55'c
    • Stock case = 82'c
The Cogent.design case runs 27'c cooler than the stock RPi and case.

RPi thermal throttling at 80'c, reducing CPU clocks:
We also need to consider the stock RPi and case, reached 80'c after only 1 minute and 30 seconds into the test. When a RPi 3 reaches 80'c, thermal throttling is automatically kicked in. This reduces the RPi clocks from 1200mhz, down to 800mhz (600mhz in extreme cases if heat cannot be reduced) in an attempt to automatically lower the heat and prevent damage to the SoC.

Code: Select all

root@DietPi:~# vcgencmd measure_clock arm
frequency(45)=884002000
So, although your RPi 3 is a 1.2ghz capable, after 1 minute and 30 seconds of full load, its most likely limited to 800mhz and the high heat, reducing the life expectancy of the SoC.

With the Cogent.design heatsink and case, our RPi ran at 1200mhz, at all times.


Guide:

Step 1: Clean the BCM chip:
We must remove all residue that is present on the BCM chip and heatsink contact area:
  • Grab your girlfriends nail varnish remover and some cotton wool buds.
  • Place a small amount of the nail varnish on the cotton wool bud.
  • Gently rub the BCM chip with the bud, until all reside is removed.
  • Dry the BCM chip by using a clean cotton wool bud to remove all remaining nail varnish.
  • Repeat the process for the heatsink contact area on the case
Image

Step 2: Apply thermal compound/adhesive:
This is required to give maximum heat dissipation efficiency through both surfaces:
NOTE: Although I was provided with a thermal compound, I decided to use Akasa-AK-TT12-80-Thermal-Adhesive-Tape instead as I want a permanent attachment.
Image

Step 3: Complete the case build:
It is critical to get a flush alignment.
  • Put the Raspberry Pi on the bottom section of the case. Check its aligned correctly and seated well.
  • Line up the top section of the case and gently place it on top of the bottom section.
  • Gently press the bottom and top section together and ensure its flush.
  • Now you can insert the screws and fix it into place.
Image

More Info / Order Online:
https://cogent.design/
Last edited by fourdee4d on Fri Oct 28, 2016 11:01 am, edited 1 time in total.
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Screwdriver
Posts: 1
Joined: Thu Oct 20, 2016 6:23 pm

Re: RPi 3 Heatsink + Case combo (55'c MAX)

Thu Oct 20, 2016 7:10 pm

That is pretty cool.

I found standard heatsinks to be useless. I added some to my pi3 with 3M thermal tape and found that the temps were higher then without the heatsinks. This case seems to be a nice solution if you have temp issues.

BTW, what types of situations cause a heat issue? Most I read about are when people are artificially slamming the CPU and not during regular use. Everything I have done with my pi has had temps below 60c..Just curious....

I still might grab one for the pure sexiness.....

tweak42
Posts: 542
Joined: Tue Mar 22, 2016 3:16 am
Location: Los Angeles, California

Re: RPi 3 Heatsink + Case combo (55'c MAX)

Thu Oct 20, 2016 9:26 pm

Man that is one solid hunk of metal. I'm not sure why there are zero pictures of the inside of the case on the cogent shop page since the heatsink properties is an advertised feature.

mhoney
Posts: 5
Joined: Tue Dec 25, 2012 9:03 pm

Re: RPi 3 Heatsink + Case combo (55'c MAX)

Fri Oct 21, 2016 2:02 am

That's a good point. I'll put some additional inside pics up tomorrow.

Thanks

AussieSusan
Posts: 48
Joined: Tue Aug 28, 2012 10:48 pm

Re: RPi 3 Heatsink + Case combo (55'c MAX)

Fri Oct 21, 2016 2:08 am

Would a 'negative' not be that the metal case would stop the Bluetooth and WiFi signals?
Susan

mhoney
Posts: 5
Joined: Tue Dec 25, 2012 9:03 pm

Re: RPi 3 Heatsink + Case combo (55'c MAX)

Fri Oct 21, 2016 2:34 am

We've done some testing (nothing scientific) and it does not block wifi or bluetooth. It reduces the range a bit, but surprisingly not as much as I thought it would be. Aren't most Apple products encased in aluminum?

gkreidl
Posts: 6345
Joined: Thu Jan 26, 2012 1:07 pm
Location: Germany

Re: RPi 3 Heatsink + Case combo (55'c MAX)

Fri Oct 21, 2016 4:39 am

The FLIRC case does the same for less than half the price.
Minimal Kiosk Browser (kweb)
Slim, fast webkit browser with support for audio+video+playlists+youtube+pdf+download
Optional fullscreen kiosk mode and command interface for embedded applications
Includes omxplayerGUI, an X front end for omxplayer

fourdee4d
Posts: 362
Joined: Mon Sep 17, 2012 10:31 pm
Location: East Midlands, UK
Contact: Website

Re: RPi 3 Heatsink + Case combo (55'c MAX)

Fri Oct 21, 2016 12:25 pm

AussieSusan wrote:Would a 'negative' not be that the metal case would stop the Bluetooth and WiFi signals?
Susan
I actually ran those stress tests with this case using the onboard WiFi over SSH. Surprisingly it works fine. Although, as mhoney already mentioned, the WiFi range (strength) is slightly reduced, but surprisingly not as much as you'd think.

Quick WiFi test:
I placed both RPi 3's in the same room, facing the same direction and roughly 30cm apart. -62dBm for the stock, -72dBm for the Cogent Design case.
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