Jun 29, 2011

Heatsink performance analysis on Pandaboard

Within our research collaboration with Aectir we made an application to select the % CPU load an monitor the temperature of the Pandaboard's OMAP4430.







We tested the board under several CPU loads and setups. The preliminar results:



SETUP
aprox.
CPU usage
(%)
max. internal
sensor temp
(C)
max. external IR temp
(C)
aprox. current
(mA)
No heatsink
20
61
67.3
840
50
69
74.4
920
70
72
77.7
970
100
76
82.5
1030
One heatsink (15x15x15mm)
20
54
57.8
840
50
57
62.0
920
70
61
64.2
970
100
63
67.4
1030
2 heatsinks
(one on each side)
100
56
60.8
1030

Here you can watch a speeded-up video of the analysis:



We also tested a bigger heatsink (30x30x15mm) that keeps the temperature in the same range as the two-heasink setup, stable at about 56 C.

8 comments:

  1. How do you keep the bigger heatsink in place? Also, can you please do a test of fan blowing through pandaboard with/without heatsinl?

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  2. @ShadowPhoenix

    In the picture you may see a steel wire across the heatsink with two white "heatsink plastic push pins" stuck into the boart holes, one on each end of the wire. That wire keeps the heatsink in place.
    With a big heatsink (from 30x30x15mm to 30x30x30mm) there is no need for a fan in a normal environment (no direct sun and ambien temp. of about 25-30 Celsius / 80-90 Fahrenheit), as the temperature never exceeds 60 Celsius at 100% CPU load.

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  3. If I use a heatsink (approximately same size) with thermal adhesive instead of using the steal wire will the result differ substantially?

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    Replies
    1. I guess you mean a thermal sticker, which has a lower performance than thermal adhesive (epoxy), and much lower than thermal paste. However, for this application it should do the job, specially if you use a 30x30x30mm heatsink, and keep the board well ventilated.

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    2. I have purchased a pandaboard and have build a custom enclosure. I have linaro running well however what utility did you use to show the cpu temp. I am new the the ARM platform...

      Thanks

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    3. There might be some driver already (to be detected by lm-sensors).

      But at the time I did it I made a custom app with a hack found in the web (once compiled you have to run it as administrator): hardwarebug.org/files/omap4_temp.c

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    4. I wasn't able to find lm_sensors compiled for ARM. I will try the script you listed. Thanks for the help!

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    5. cat /sys/bus/platform/devices/temp_sensor_hwmon.0/temp1_input
      will give you the temp in mC (milliCelsius)

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